Having established himself as a useful amateur, Owen Delaney is asked to check out what might have prompted the suicide of a promising female grad student at the university in Philadelphia where he teaches. Encouraged by the dead girl's father, he suspects foul play, although no one other than the grieving father supports his suspicions. But, with the help of a few interesting friends and the surprising help of his wife, he gets an unexpected confession to murder from another grad student who claims he was coerced by a criminal mastermind whose activities the dead girl had inadvertently uncovered. Believing the story and sympathetic to the young man's plight, Owen and his wife begin to put together a case against the mastermind. When the mastermind learns that Owen is on to him, Owen and his family become targets. In an exciting turn of events, the family survives and a crude form of street justice is done.