To me, Richard Widmark's best film is Time Limit. It's about an army inquest into a soldier who admits that he helped the enemy when he was a POW during the Korean war. Widmark is the Colonel in charge of the investigation, and Richard "He Walked By Night" Basehart brings his A-game to the role of the soldier. Any other colonel might just connect the dots and recommend a court martial - Basehart's Maj. Harry Cargill admits he gave broadcasts for the North Koreans, signed a paper saying the Americans were doing germ warfare, and was attempting to indoctrinate the other POWs in formal "classes" that the North Koreans had to try to brainwash them. All of the POWs in the same camp he was in verify that Cargill did these things.
But Cargill refuses to tell Widmark's Colonel William Edwards WHY. And he doesn't seem to care he could be, heck, probably will be executed for treason without some defense. With Cargill's past stellar military record, including in WWII, Edwards will not finish this investigation until he gets a "why". But Cargill has talked to nobody about why he did what he did - not even his wife. And Colonel Edwards is being pressured by his superior, a General whose son died in the same POW camp that Cargill was in, and even by Martin Balsam as a particularly irritating sergeant, to recommend prosecution and wash his hands of the matter.
And then Edwards notices that the descriptions of the back-to-back deaths of two soldiers in the POW camp the day before Cargill seemed to turn traitor are identical - as in word for word each time by each soldier. Is there a Manchurian Candidate situation going on here, or something else entirely? The plot twist at the end is the farthest thing from a gimmick, and is infinitely better presented and far less Hollywoodish than the sanctimonious speech by Jose Ferrer at the end of The Caine Mutiny, although I like that film too, for different reasons.
Check it out if you get the chance. WWII films always seem to get the spotlight, but this one is a forgotten jewel about a forgotten war.