'Mackrell and McArthur, Private Investigators', that's what it said on the door to the office. Tireless determination and dogged pursuit of justice are what went on behind that door. Gatwick 'Mac' McArthur sat in the office one grey Monday afternoon. The rain lashed against the grime-encrusted window like a cat-o-nine tails landing on the back of a scurvy buccaneer. The city had been quiet - too quiet - recently, and MacArthur was growing desperate for some unspeakable criminal deeds to be committed. Where were they all when a fat pay cheque was needed? The robbers? The muggers? The killers? They seemed to have cleared the streets. But when the rain stopped, they would emerge, blinking in the sunlight, ready to wreak havoc on this trusting community. And when they did, he - Gatwick McArthur - would be ready and able to meet...

"Oh, fiddlesticks! Charlie, my pencil's snapped." The voice was pleasantly high and positively reeked of good schooling.

"Sharpen it then," replied a second voice, this one a little more accented. Teesside? Durham, possibly?

"The sharpener seems to have disappeared."

"Try the drawer at the bottom."

"Ah, marvellous!"

McArthur happily sharpened his pencil as the other voice emerged from behind a bookcase.

"Got it," it said, brandishing a chewed biro, now covered in grey fuzz. "I wish you wouldn't keep letting it roll off. It's filthy on the floor."

"I'm sorry. You know there's a rather bothersome slope at this side of the office."

"Can't you shove some cardboard under the legs of your desk to stop it wobbling?"

"My dear Charlton, if we can only afford one pen and one pencil for the office, I think wasting good cardboard simply to even out my desk is going to be well beyond the limits of our available currency."

"You mean, in plain English, we're too poor?"

"Correct."

Charlton 'Charlie' Mackrell rolled his eyes at his partner and returned to his own desk on the less-sloping side of the room.

* * *

McArthur sat and stared out of the window at rain that still came down like a tart's knickers on a busy weekend...

"Can I say that?" said McArthur, putting his pencil the desk then quickly snatching it up before it was claimed by gravity and the dusty floor.

"What are you on about now?" said Mackrell.

"I'm writing my memoirs, and I'm uncertain about some of the metaphors I've penned."

"You mean 'pencilled'."

"Well, yes, I suppose."

"Let's have a look."

Mackrell wandered over to his partner's desk and scanned the handwritten sheets.

"Came down like a tart's knickers?'" he sniggered. "Scurvy buccaneer? What is this rubbish?"

"It's how a detective's memoirs are supposed to be written."

"No, it's how American detectives' memoirs are supposed to be written. You're from Tunbridge Wells. Via Marlborough School and St John's College. I think your writing style needs to be a bit more appropriate."

"You're wrong," said McArthur sullenly. "This is how detectives are supposed to write, and write like this I shall."

Mackrell started to move back to his own desk, then stopped.

"Never mind metaphors, how can you possibly be writing anything at all? I mean, how many cases have we had since we set up this business."

McArthur counted slowly on his fingers before announcing, "Three".

"Three. Not much when you've got a whole book to fill."

"Well, I thought I'd start writing those up while things are a little slow, and then add new cases as they appear."

"Nice idea, but it's been months since anyone walked through that door."

"They will."

* * *

When the dame stepped through the door, she hit the office like a hurricane. I'd seen legs like that before, but they were on a gazelle. Sadly, I'd also seen what lions could do when they scented their prey on the savannah. I just hoped that, by the end of this case, I wouldn't be cleaning up that sort of mess.

"Sorry - am I interrupting?" said the woman who had just walked into the office out of the rain and now stood in front of McArthur's desk, dripping. McArthur's nose emerged from his notebook.

"Not at all, my dear, not at all. I was merely writing up a few of our recent commissions."

He closed his notebook with a snap and thrust it into a drawer, before realising that, if he was going to take a statement from this woman, it might be needed. He retrieved it and grinned at the woman sheepishly. She stared back impassively. Mackrell leaned back in his chair and appraised the new arrival. If she did have the legs of a gazelle - he'd have to have a quiet word with McArthur about that - she was keeping them well hidden. Given the state of the weather, mind you, that was hardly odd. She was dressed, very sensibly in Mackrell's opinion, in a long rain-coat and a pair of brown leather boots. Barely a hint of African grasslands. On the other side of the office, McArthur attempted to compose himself and gave a smile he hoped could be described as winning.

"I'm Gatwick McArthur, and my partner Charlton Mackrell is also in attendance. Please do take a seat, Miss..?"

"Williams." She looked around the office, trying to identify something to sit on, without much success. Mackrell leapt to his feet and dragged his own chair to where she stood.

"We're having our furniture upholstered, Miss Williams," he improvised hurriedly.

"A result," chipped in McArthur, "of the constant wear and tear imposed by the stream of people requiring our assistance." The woman perched herself on the chair that Mackrell proffered. No-one spoke, and the sound of the rain grew more audible in the stillness.

"My brother's been killed," she said eventually. McArthur glanced at his associate.

" Killed? And you know the assassin?"

"If I knew who killed him, I wouldn't need..."

"...a detective," McArthur interrupted. "Indeed. What I meant was, do you suspect anyone at all?"

"The police say it's a serial killer. They've been looking for him for some time, but they're baffled. I thought a private detective might have something else to offer."

"I should certainly hope we can," replied McArthur smoothly. "But let me begin by saying how sorry we are for your loss."

"Thanks," said the woman stiffly.

"When was he killed?" said Mackrell.

"From what the police have told me, it was Wednesday afternoon. It was lunchtime and he'd left the office to get some food."

"He didn't make it back to the office?"

"His body was found in Regent's Park, dumped under some trees."

"And was it," said McArthur, "his habit to take a lunchtime stroll?"

"Whenever possible."

"In what manner did he meet..." Mackrell rolled his eyes and cut his partner off.

"How was your brother killed? I'm sorry to ask, but the more we know the better."

"Don't worry. I want this lunatic found before anyone else has to suffer. My brother died from - what did the coroner say - by blunt-force trauma to the occiput."

"Or, in plain English, he was hit on the back of the head until he was killed. What makes the police so sure that that isn't a one-off?"

"My brother was the third body to be found, apparently. Each one had a strange mark on the cheek, and each time the killer left a card saying 'Titivillus'."

"How bizarre!"

"It's certainly got the police puzzled."

"Well, Miss Williams, we'll get to work straight away," said Mackrell reassuringly. "Before you go, can you let us have your brother's name and address?"

"His name was Steven," she said, and for the first time during the interview a tear crept down her cheek. McArthur passed his notebook and pencil across the desk and she jotted a few lines before getting to her feet.

"You'll let me know as soon as you make any progress?"

"Of course we will. Where can we contact you if necessary?"

"You can get me on this number," she said, and pulled a business card out of a leather wallet.

"We'll be in touch," said Mackrell, escorting Miss Williams out of the office. She closed the door behind her, and the two detectives stood contemplating their new client, silent but for the sound of a pencil rolling off a desk and onto the floor.

* * *

They say every man has his demons, and Mac had more than sufficient. He sat back and put his feet on the desk, taking long draughts from the bottle of redeye he kept hidden under a loose floorboard. The dame had left them with a dead body, a card and a riddle. Only God knew how they were going to get on the right track this time, and he wasn't telling.

"Now look." Mackrell stood peering over his partner's shoulder as the latter's pencil continued its frenzied scribbling. "You don't have any demons, you don't drink 'redeye', we don't have any loose floorboards, you don't believe in any gods, and the phrase 'more than sufficient' should not be used by anyone desperately trying to sound hard-bitten."

"So what do you suggest?"

"I think you should stop pretending to be Sam Spade and help me do some digging."

"Very droll. So what have you been doing while I've been trying to make our lives sound a little more attractive?"

"I've been trying to find out who or what Titivillus is, and I think I've succeeded."

"In what manner?"

"I looked it up on hootoo."

"Brilliant!"

"Apparently, Titivillus is a demon that takes printed documents and inserts typograhpical errors."

"So we're on the trail of a fiend from hell?"

"No, you pillock! I think we're looking for someone with an interest in typesetting."

"I see."

"Has your contact at the mortuary faxed over those images of the bodies, or is our fax machine still buggered?"

"It is, but I asked her to fax them to the bookmakers. They should be there soon."

"Great, we can pick them up on the way to Steven Williams' office. And pass the racing pages over; I'll see if there's anything worth a flutter."

* * *

In this job, you see all sorts of people, in all sorts of places, in all sorts of moods. Most of them grim, and all of them in need. Finding out what they need can be half the battle. And the other half of that struggle? Let's just say that you can climb inside a killer's head, but it's never pretty.

"Mac, this is gibberish."

"Give that back immediately!"

"You'll bring our profession into disrepute," said Mackrell, returning his companion's notebook with a shake of his head and a look of sorrow.

"This isn't just a profession. It's a noble calling."

Mackrell nodded. "If this was a real profession, we'd be sitting in a taxi instead of standing here waiting for a Jubilee Line train to appear."

"That's not what I meant, as you know perfectly well."

"While we're waiting, let's have another look at those photos you're carrying.

"Let's see. This is the first body, a Kate Addy." He passed the photograph over, and the two peered at it, trying to make out the strange impression on the young woman's left cheek. "The second one is a Siobhan O'Flaherty, although her hospital name badge is quite smudged in this picture, and this is the photo from Steven Williams."
The marks on the cheeks of the three bodies were all different. That of Kate Addy was almost circular, while Siobhan O'Flaherty had a zigzag line, and Steven Williams a single straight scratch just below his cheekbone. The two detectives continued to pore over the photographs after they boarded the train, achieving little in the way of enlightenment before they left it again at St John's Wood.

"Did you know that St John's Wood is the only Tube station that doesn't contain any of the letters of the word 'Mackrell'?"

"Charlton, that is one of the least useful pieces of information you ever seen fit to communicate."

"No need to get sniffy."

* * *

If the place had some serious work put into it for a few years, it could just about qualify as seedy. As it stood, it wasn't a place you'd keep a dog, and McArthur had known some pretty despicable kennels.

It's jolly nice here, isn't it?" said McArthur as they entered the private hospital where Steven Williams had worked in what used to be called Personnel.

"I wonder why they call it Human Resources these days," wondered Mackrell, watched by a stern-looking receptionist as they stood trying to work out which of the numerous identical corridors they needed. They were interrupted by a shout from one of them and a man ran out looking as white as a sheet.

"I think he's dead!" he announced.

"The Professor?" asked the receptionist, stunned. The man nodded.

"He's lying in his office, covered in blood. It looks like he hit his head when he fell."

The receptionist picked up a telephone and dialled.

"Dr Owen, please come to reception as quickly as possible. There's been an accident and Professor Robinson may have been..." She stifled a sob and wiped her eyes with a tissue. Mackrell stepped over to the reception desk and spoke gently to the two members of staff.

"I'm Charlie Mackrell and this is Gatwick McArthur, my colleague. We're detectives investigating the death of Steven Williams last week. It's possible that his death and the Professor's are connected."

"But the Professor was harmless. Why would anyone want to kill the old buffer?"

"That, sir, is what we're here to discover," said McArthur carefully. "What were you doing in the Professor's office?"

"Delivering his letters."

"At this time in the afternoon?"

"He prefers them to be delivered when he's ready to open them, rather than have them left on his desk getting lost in the clutter."

"Very well. Perhaps we could take a look at the scene of the offence? "

The group moved into the Professor's office where the body lay, looking in horror at the gash in his head from which a pool of blood had seeped. McArthur pointed at the mark on the Professor's cheek that they'd expected to see.
"It's a curve, different to all the others," he said, moving the Professor's hair aside carefully.

"This can't have happened long ago," said Mackrell, looking around the room. "Has anyone entered or left the room while you've been in the entrance hall?"

"No, I don't think so," said the receptionist, "unless..." She stopped. McArthur turned and stared at her keenly.

"Do tell."

"It was just one of the maintenance guys - Bob I think he's called."

"Presumably he would have had a perfectly valid reason to be coming out of the Professor's office in plain sight of one and all?"

"He was carrying a bag of tools. I just assumed..."

"...he'd come to attend to the fixtures and fittings? A perfectly natural assumption." He turned to Mackrell with a worried look. "He appears to have become careless. Perhaps he realises that capture is inevitable and intends to go out with a massacre." He turned to the two hospital employees. "Where might we locate this 'Bob' fellow?"

"In the maintenance department on the first floor."

"Good. Then we shall proceed. In the meantime, I suggest you request the presence of a police officer. I fear that your Dr Owen's ministrations may be somewhat ineffectual."

* * *

The clock ticked on as McArthur neared his quarry. He knew he was close by the smell. It was the smell of terror. The terror of a perpetrator about to be brought to book. It was also the sweet smell of success. But it was a success that still had to be won, and that was always going to be fraught with difficulties...

"I hope you're going to include me in these memoirs," asked Mackrell as they walked down the corridor.

"Of course I shall. I was thinking of presenting you as the laconic, battle-hardened veteran of a hundred impossible assignments."

"On second thoughts," reflected Mackrell, "perhaps leaving me out would be better. I'd hate anyone I know to think I approved."

"Your support and encouragement of my literary endeavours are most welcome," said McArthur peevishly.

"Never mind that, we need to get hold of Bob and find out if he's our serial killer."

They burst through a door marked 'Facilities', where an elderly man stood with a red-stained cloth, wiping a hammer. On the floor lay a woman, clearly dead, blood oozing from her head and pooling around the man's feet.

"I won't take it any more," he yelled. Mackrell nodded at his partner and began edging around the room.

"So, Bob, what is it that you're not going to take any more?" asked McArthur, focusing the man's attention.

"All of them," shouted Bob, "wasting letters. Wasting good ink and paper, and my time, for no reason than their own selfishness."

"And the 'them' to whom you're referring?"

"All of them, strutting around with their little badges, taking up far more space than necessary."

"Space in the hospital, would that be, or something different?" By this time Mackrell was moving around behind the man, who was still distracted by McArthur's interrogation.

"Space on the page," shouted Bob passionately. "Wasting my time filling up the pages when they're not essential. Don't need them at all. Nasty, horrid..."

Mackrell seized the man from behind and forced him to the floor, dashing the hammer from his hand and keeping his arms firmly pinned.

"It's over," he said, panting slightly after the struggle.

"Nooo..."

"I'm rather afraid," said McArthur, "that that's the end of your little killing spree. Now, are you going to tell us exactly what drove you to kill five people who were completely innocent?"

"Never," said the man, as Mackrell struggled to clap the man's wrists in handcuffs. Finally succeeding, the detective sat back and looked sadly at the self-styled Titivillus.

"Double letters."

"I beg your pardon," said McArthur, "but do you actually know the reason for this madness?"

"Yes, I think I do," replied Mackrell. "It's all about double letters. I'm sure Bob here used to be a typesetter, hence the name Titivillus, correct?" Bob remained silent, as Mackrell got to his feet. "By some twisted logic, he decided that people with double letters in their name were taking up 'too much space' and had to be killed. Kate Addy. Steven Williams."

"What about the Professor?"

"Bastard!" said Bob, suddenly. "Waltzing around the place with 'Professor' on his badge, on his nameplate, everywhere you looked. He could have put 'Prof', or even called himself 'Doctor', but no, not his lord high professorship."

"What I can't work out though," said Mackrell, "is how Siobhan O'Flaherty fits the pattern."

"I believe," said McArthur, "I can shed some light on that little puzzle. You'll recall me observing that her name badge was smudged and difficult to see? It is my conjecture that Titivillus here thought it said O'Flannery. Poor Siobhan was killed in error."

There was a moment's silence as the two detectives considered the fate of the five victims, before the door burst open and two uniformed policemen charged into the room.

"At ease, gentlemen," said McArthur reassuringly. I think you'll find that the case has been solved quite successfully."

"Oh god, not you two," said one of the police officers. "Look, stay here and don't move a millimetre. There'll be someone along to ask you some questions soon." With that, they relieved Mackrell of his charge and dragged the prisoner off to the cells. Mackrell and McArthur looked at each other as medics arrived to remove the body that had lain on the floor throughout the proceedings.

* * *

McArthur sat in his chair and gazed out into the darkness. The glow of a million neon lights gave the city an air of unreality as, somewhere out there, another killer was safely locked away for good. These were the moments he'd dreamed of when he was growing up on the wrong side of the tracks; the moments when you felt that one man could make a real difference.

"So," said Mackrell handing the notebook back to McArthur, "you decided to write me out after all."

"I just thought it read a little better. I could perhaps find a small part for you if you didn't want to be completely omitted?"

"I'll let you choose."

McArthur put the notebook into his desk drawer and shrugged. "Perhaps I should come back to it tomorrow." There was a pause, each of them lost in their thoughts, when the mortuary photographs sitting on McArthur's desk reminded him of the one unresolved issue. "I say, Charlie, did you ever work out the meaning of those strange marks on the victims' cheeks?"

"Our friend Titivillus etched each victim with their double letter. 'D' for Kate Addy, 'L' for Steven Williams, 'N' for who he thought was Siobhan O'Flannery, and 'S' for the Professor."

McArthur gave a shudder. "Quite, quite horrible. Still, it does no good to dwell. I'll see you tomorrow." He stood up and pulled on his coat, looking across at Mackrell, who was busily writing up the final details of their latest mission. "You know, I think I could quite easily live without double letters. Perhaps they are unnecessary."

"Rubbish!"

"No, really."

"Cobblers!"

"Hmm... I think we'll have to agree to disagree."

"Boll..."

McArthur stepped out of the office and closed the door.