Nichols and Stevens must discover the identity of a killer before another couple is forced to make the most difficult choice. Abel, a deranged social psychologist, forces Ted to choose whether to kill himself or his wife Linda. This is part of a series of experiments Abel is conducting to understand and vindicate his grandfather, Leon. Leon was a concentration camp survivor who was forced by the Nazis to kill himself or his wife. Abel is haunted by the choice and sets out to prove his grandfather did what anyone would have done in that situation.