The Floating Zombie by D.F. Jones
Berkley Medallion, 1975
Price I paid: $1.25
Before AT1 had ground down the slipway unchristened―rightly, said seamen, for it would be a ship with no soul―it had been dubbed “Zombie.” That sinister name would stick, and prove its accuracy. AT1 was a robot-ship, a ship with no crew, only a tiny security force of 3 men and a woman. “Invulnerable,” said its inventors, and “foolproof.”
But it was neither―not if one of the 4 security guards was an insane, ruthless killer. And if the greatest and most powerful self-contained nuclear reactor in the world fell into the hands of such a person, the whole world was in peril!