Sgt. Ryker (Lee Marvin) is an American soldier charged with treason during the Korean War, he is court-martialed and prosecuted by Capt. David Young (Bradford Dillman) and convicted and sentenced to death.
Ryker's wife, Ann (Vera Miles), insists that her husband received an inadequate defense. She believes his story that he had been on a secret mission, assigned by a superior officer who has since died and can no longer vouch for him.
Capt. Young believes Ryker is guilty, but he, too, thinks Ryker received an inadequate legal defense. He persuades the commanding general to give Ryker a new trial. The general reluctantly does so, but he insists that this time Young must serve as Ryker's defense counsel. Ryker has already resigned himself to his fate, and has to be persuaded to go along with the retrial. As it unfolds, all the evidence is damning to Ryker, the best Young can do is establish that Ryker's version of events is not impossible. The defense is also undermined by several of Ryker's lies and omissions, which are exposed during testimony at the trial, and also by Ryker's occasional fits of temper. A further complication ensues when a romantic attachment develops between Young and Ryker's wife. Ryker is furious when he realizes it has happened, and the general on hearing about it tells Young he will be court-martialed as soon as Ryker's trial is over.
The prosecutor, Maj. Whitaker, unearths new evidence damning to the defendant's case, and all seems lost. At the last minute, however, Young learns some information from a Sergeant Winkler, which verifies some aspects of Ryker's claim, and which when followed up on by Young, is enough to compel that Ryker be set free.
