Which 1952 film noir has Charles McGraw and Marie Windsor on a train protecting a witness?

Which 1952 film noir has Charles McGraw and Marie Windsor on a train protecting a witness? The answer is The Narrow Margin.

Richard Fleischer directed this tightly constructed thriller, with McGraw as Los Angeles detective Walter Brown. Brown escorts Frankie Neall, played by Marie Windsor, from Chicago to Los Angeles so she can testify before a grand jury against organized crime. The train journey becomes a claustrophobic battleground as gangsters try to identify and eliminate her.

The story’s most important twist involves mistaken identity: the woman Brown initially protects is a decoy, while another passenger, Ann Sinclair, is the real mobster’s widow. That reversal makes the title’s “narrow margin” feel literal, as survival repeatedly depends on split-second judgments in cramped compartments.

The film was shot economically, using handheld camera work and rear projection to intensify the confined train setting. It runs only 72 minutes and was nominated for Best Motion Picture Story at the 25th Academy Awards. A 1990 remake starred Gene Hackman and Anne Archer.