At Sanibel Island, Florida, dozens of identical shoes float in on the tide and are washed up on the tropical beach—each one with a severed human foot inside. Called away from vacation, Agent Pendergast reluctantly agrees to visit the crime scene, and is quickly drawn in by the incomprehensible puzzle. In this 19th investigation (after Verses for the Dead), all trails lead back to a powerful adversary with a sadistic agenda, someone who sees Pendergast as the ideal subject for a malevolent experiment.