Michael Douglas and Karl Malden in The Streets of San Francisco (1972)

A pair of plainclothes homicide detectives, Lieutenant Mike Stone and Inspector Steve Keller, cruise the streets of San Francisco, California solving a variety of crimes, usually involving murder. Stone is the street-smart twenty-year veteran cop, and Keller is the college-educated rookie. Much of the series’ success was due to the friendly by-play and relationship between the two leads.