LAPD detective Sgt. Tom Valens (David Janssen) is a ten-year veteran of the force who has had more than his share of hard luck lately -- his marriage is a wreck, and he hasn't fully recovered from a serious wound suffered in the line of duty a year ago. He and his partner, Sgt. Ed Musso (Keenan Wynn), are working a stakeout one night at the Seascape Apartments, in hope of catching a killer who has already claimed three victims in that part of the city, when he confronts a man seemingly trying to sneak off the premises. The man tries to run, stops when ordered but starts to pull a gun, and Valens shoots him dead. The deceased turns out to be Dr. James B. Ruston, a well-known humanitarian and pillar of the community -- worse yet, the police can't find any trace of the gun Valens says he saw Ruston pull. Valens' nightmare builds gradually, as he's first assigned to a desk, then hung out to dry by an indifferent coroner (Carroll O'Connor) at an inquest, suspended from the force, and then indicted for manslaughter by a crusading prosecutor (Sam Wanamaker) with a personal ax to grind. Villified in the press and by protesters in the street, Valens has few even slightly sympathetic ears around him -- his partner, his captain (Ed Begley Sr.), and his soon-to-be-ex-wife (Joan Collins) -- and even fewer allies. The one attorney (Walter Pidgeon) with enough juice to fight the case on an even footing with the DA says he would only plead him guilty and try for a deal, based on his understanding of the law and of juries; and the one public pundit (Steve Allen) who takes his part is doing so for the most cynical of reasons. Valens realizes that the only way to save himself is to first prove that the so-called victim wasn't quite the candidate for sainthood that he seemed -- why did he run? -- and to find the missing gun. To do all of that, he's got to confront the victim's aggrieved patients (Lillian Gish), his alcoholic widow (Eleanor Parker), and his employees (Stefanie Powers), all of whom have every reason to hate Valens. He starts to dig into the doctor's finances and finds some anomalies that no one can explain (or wants to look at -- they'd rather hang Valens), and as he puts together the pieces of the puzzle, helped by a sympathetic tenant at Seascape (George Grizzard), Valens finds himself pursued by the doctor's thug of son and his friends with mayhem on their minds -- and someone else with a deadlier agenda.