An alien structure is discovered on the Moon. It may have been there for a million years. Every man who enters it dies. After the use of a matter transmitter to send duplicates to the Moon, the person, knowing they’re going to die, goes insane. The person on Earth and the duplicate on the Moon know exactly what’s going on.
The Director of Science and VP of Research for Consolidated Electronics, Dr.Edward Hawks, needs to find someone who doesn’t fear death and may even embrace it. He thinks he may even need a psycho. The company personnel director leads him to Al Barker, He’s a former assassin for the OSS as well as a daredevil. He’s already crashed a hydrofoil and will soon enter the Grand Prix with a car he built himself. He’s also a huge jerk.
He seems to take it all lightly as he’s fitted out for the matter transmitter, knowing that he’ll die over and over. The most anyone has lasted in the structure is under three minues. Dr. Hawks gives him every chance to back out. He doesn’t. Barker’s ego is in for a huge blow.
Along with the SF elements, the book is a great character study of Barker and Hawks as they go through their personal lives and the transmitted Moon trips. No wonder the book impressed Ben Bova and James Blish.