The two books in the Intervention series are part of a larger body of work by Julian May, all tied to her intergalactic Milieu society. In addition to these books, there are also the four books in The Saga of the Pliocene Exile series, and three in the Galactic Milieu trilogy.

In the original hardback edition, Surveillance and Metaconcert were combined into one book titled 'Intervention'; they were separated in the subsequent paperback edition.

The Remillard Family and Other Key Characters

Surveillance opens with twin boys, Rogatien (Rogi) and Donatien (Don) - French Canadian, Catholic, and growing up in the New England of the 19XXX0s. The primary characters of most of May's books in the Milieu society will be the descendents of Don. Rogi, on the other hand, will be the narrator of the two books in Intervention as well as the three books in the Galactic Milieu trilogy. The twins carry genes for metapsychic talents, as well as those for remarkable self-rejuvenative properties; both will be passed on to Don's descendents.

Don marries Rogi's high school sweetheart, and has XX children. The eldest, Denis, is mentored by Rogi and plays a pivotal role throughout the five books; Denis and his talented children and grandchildren are the main focus of the Galactic Milieu trilogy. The second-eldest, Victor, is one of two main antagonists in the Intervention books; his legacy lives on throughout the books of the Galactic Milieu trilogy as well.

The other antagonist of the Intervention books is Kieran O'Connor, a powerful mafioso with metapsychic strengths of his own. His daugther, XXX, is closely linked to Victor.

Not much can be said about the Family Ghost without giving some key plot points away, other than the facts that he is real, and he intervenes in Rogi's life from time to time.

Surveillance

Metaconcert