Humanity is in complete isolation, and only a few of its representatives live on the planets of the Commonwealth. A private detective from Earth, Jack Markoff, strives to be among them and therefore immediately agrees to cooperate with aliens in the investigation of a series of murders committed in prosperous worlds by a maniac - a man. A seemingly simple mission turns into a mortal battle for Makaroff not only with a maniac, but also with participants in a truly galactic conspiracy.