The woman who had been dead for one to two months- and who was three months' pregnant- brings Detective Sergeant Petrella into the little kingdom of the Metropolitan Water Board and its reservoir and has links with the disappearance of a mob-jewel-theft head, Monk Ritchie. When Petrella -- ready to fight to see justice is done -- takes up skin diving, the circle, with another body, narrows, and British police open up an unexpected impersonation and a clever crime dodge. Smooth-meshed mechanics.