Captain Nebula is being held on Earth by humans who are at best unwitting dupes of, or at worst, active agents of the evil galactic overlord Drago.
Or at least, he believes he is. Dr. Weaver, the psychiatrist under whose care and control he is under, is frustrated at being unable to find a chink in this delusional behaviour, as the man calling himself Captain Nebula has an answer for everything.
Wryly humourous, with Resnick opting to provide the answer at the end, rather than the Algis Budry’s approach in ‘Who?’, which leaves the reader to decide.