A young wife is shot by an unknown assailant when she drives with her ex-con husband to an isolated woods in search of their dream home. No one even reports the couple missing until after the police find them dead in the snow. The wife's sister is a wealthy spinster, who takes her time even coming to Chicago, claiming her brother-in-law was threatened with death by a blackmailer. Det. Ballinger suspects the sister knows more than she reveals.
A boxer's (Lancaster) life is being threatened soon after another fighter dies after fighting with Lancaster. Suspicion falls on the other fighter's trainer who feels Lancaster is responsible for the death of the other fighter.
Lieutenant Ballinger searches for a mentally ill young woman who shot a psychiatrist, hoping all the while that he can also find sufficient evidence to obtain a felony conviction against the charlatan who was "treating" her.
2 innocent men are iced by a currency exchange bookkeeper, to disguise her embezzlement. The sultry femme fatale's yarn that it was a heist gone bad makes sense at first, because of a wave of such robberies on Chicago's Far East Side. But the murdered customer Halper checks out as a solid working stiff, plus the other stick-ups were solo jobs while this was supposedly a 2 hood hold-up, so M Squad's debonair Lt. Ballinger's sic-ed on the case to soften up hard boiled Ora Kane.
Danny Mitchell is trying to find an engagement ring for his girl when he mistaken for a thief by the store owner. A fight convinces him he has killed the old man-- as such Danny's on the run! Ballinger is called in to find the kid before he gets into real trouble.
The wife of a brain surgeon is abducted and threatened with death if the surgeon goes ahead with an emergency operation to save a critically injured police witness that can implicate a loan shark in two murders.