City Heat - Richard Benjamin, Blake Edwards

Kansas City in the 1930s: private investigator Mike Murphy's partner is brutally murdered when he tries to blackmail a mobster with his secret accounting records. When a rival gang boss goes after the missing records, ex-policeman Murphy is forced to team up again with his ex-partner Lieutenant Speer, even though they can't stand each other, to fight both gangs before KC erupts in a mob war.