|Galactic Milieu Series|
|Jack the Bodiless|
Intervention (its full name being "Intervention: A Root Tale to the Galactic Milieu and a Vinculum between it and The Saga of Pliocene Exile") is the hardcover only prequel to the Galactic Milieu Trilogy that was later split into two mass market paperbacks: Surveillance and Metaconcert.
This book deals with the history of several family lines with strong metapsychic potential, especially the Remillards. This line begins with twins Rogatien (Rogi) and Donatien (Don), whose mother died giving birth to them. They discover that they have unusual mental abilities (which admittedly turn out to be far less than those of later generations of metapyschics). Rogi is a milder mannered man, who becomes sterile through mumps. Don is distrustful and malicious, but handsome and charming, and steals Rogi's girlfriend Marie Madeleine "Sunny" Fabré.
From an early age, Rogi was visited by an entity he called "the Family Ghost", and it is this entity who commanded Rogi to write his memoirs. The Ghost first rescued Rogi as a child, and many years later rescued Don after Rogi tried to kill him in a rage for stealing his girlfriend. The Ghost tells Rogi that he is sterile, but would have an important role in guiding Don's key descendants.
Rogi becomes close to Don and Sunny's firstborn child Denis. Denis is a precocious child, and quickly learns to master many metapsychic faculties, greatly exceeding those of Rogi and Don, in addition to excelling intellectually. Rogi becomes like a real father to him, while Don is always out getting drunk at night. Rogi and Denis start to search for people with similar powers. Meanwhile, Don and Sunny raise their nine other children, including the monstrously evil second-born Victor, who terrorizes his younger siblings and suppresses their mental powers.
Rogi learns of a Jesuit monastic school and manages to get Don to allow him to send Denis there. This leads to Denis attending Dartmouth College due to a new programme for "special students". He becomes prominent in many fields, particularly psychology and the understanding of "metapsychic" abilities, eventually becoming the "Grandfather of Metapsychology". Subsequent research yields results in many places in the world and Denis organizes yearly meetings within the secret metapsychic community.
At the same time, Victor is plotting with the sociopathic gangster metapsychic Kieran O'Connor to bring down the government with their metapsychic powers. This culminates in a showdown at the end of the book where Denis calls out to all the present and absent metapsychics of goodwill to join in a "metaconcert" against an attack by Victor and Kieran. The watching Milieu agents invisible in the sky hear this call, and the subsequent metaconcert, and therefore intervene. Victor, meanwhile, goes after Rogi who has learned too much. Through his metapsychic power of creativity, Rogi uses a mental laser to put Victor into a vegetative state. Rogi never understood how he could have overcome such a powerful metapsychic as Victor, until the Family Ghost reveals decades later that he assisted.