A two-man mission to Venus fails and is aborted; when it returns, the Captain is missing and the other astronaut, Harry M. Evans, is unable to explain what has happened. Or, conversely, he has too many explications; his journal of the expedition-compiled in the mental institution to which NASA has embarrassedly committed him-offers contradictory stories: he murdered the Captain, mad Venusian invaders murdered the Captain, the Captain vanished, no one was murdered and the Captain has returned in Evans's guise.
As the explanations pyramid and the supervising psychiatrist's increasingly desperate efforts to get a straight story fail, it becomes apparent that Evans's madness and his inability to explain what happened are expressions of humanity's incompetence at the enormity of space exploration.
