A policeman is killed while on a routine visit to a house. The killer turns out to be an old friend of Sam's, the gentlest man Sam has ever known. Arrested he admits that he killed the policeman and then, while in a cell, kills himself.

Sam is determined to find out what changed his friend and investigates. He finds radiation in the jawbone and uncovers the story of a military experience in Germany that involved torture and, possibly, the force-feeding of a radioactive drug. Can Sam prove that this is what caused his friend to kill and restore his good name?