 Detective Lt.Bill Bannister (Kent Taylor) has the assignment to run down an unknown gang of terrorists spreading a net of crime over the city. Aiding him is Detective Tim Nolan (Robert Armstrong), news photographer Vicki Logan (Irene Hervey) and reporter Happy Haskins (Richard Davies). Bill finds that the gang s leader is a mysterious Professor Mortis (Ralph Morgan) and the gang is made up of known criminals officially listed in the police records as dead. Each has become of member of Mortis  "League of Murdered Men" after seemingly committing suicide by hanging while on death row. Bill eventually, after surviving a plane crash, being dynamited, dropped down a well and other nuisances, tracks the gang to two hideouts; a subterranean cell beneath the city s subways and a suburban mystery house.