In the latter 1960s Stewart McMillan, a Navy veteran and attorney, is named commissioner of the SFPD. In this capacity he becomes involved, to a degree unusual for police commissioners, in a series of criminal investigations, frequently aided by his wife Sally, a mystery buff who is well-meaning but frequently of an inferior mind but nonetheless is able to prove herself. Also assisting Commissioner McMillan are his partner, Sgt. Charles Enright, a loyal if somewhat ineffectual officer who worked for a private detective agency and thus gained the experience needed to join the force, and McMillan's tart-tongued housekeeper.

Both Susan Saint James and Nancy Walker left the show at the end of the 1975-1976 season. St. James because of a contract dispute, and Walker because she had just signed a contract with A.B.C..