The Narrow Margin (1952) on Netflix

When a mobster's widow decides to testify and provide names of others involved in evil deeds, she goes undercover to avoid being killed. Onboard a train going cross-country, she's being escorted in order to testify. Cop Walter Brown and his partner are assigned the task, but the mob are on their trail, attempting to make sure she never reaches her destination. —Col Needham assassinlittle boyundercovertrain stationwoman in jeopardy142 morePlot summaryAdd synopsisTaglines"She's the one for that bullet--not me!" - Night train West---carrying two mystery women. The secret of one can blast the crime syndicate wide open---and the key killers dare not let it happen!GenresCrimeDramaFilm-NoirThrillerCertificateApprovedParents guide