Crossfire is not only the first B-movie to earn an Academy Award nomination for Best Picture, but it's also one of the first Hollywood films to tackle anti-Semitism in America. It's also an excellent film noir thriller in its own right.
Crossfire was based on the 1945 novel The Brick Foxhole by Richard Brooks - the same Richard Brooks who later went on to direct (and write the screenplays for) Blackboard Jungle (1955), Elmer Gantry (1960), and In Cold Blood (1967), among other classic films. The original novel dealt with an ex-soldier who was murdered for being gay. However, when RKO was adapting the film for the big screen, the Production Code Administration forbade any mention of homosexuality in film at the time, so the screenwriters made the victim Jewish instead. (Kinda ironic, given that PCA director Joseph Breen's own anti-Semitism is well documented.) Although anti-Semitism was a topic previously left mostly unaddressed, the scope of the Nazi atrocities that were revealed at the end of World War II and the Nuremberg trials spurred filmmakers to finally confront this issue on the big screen.
In Washington DC, the police are investigating the recent killing of Joseph Samuels (Sam Levene), a Jewish man last seen in the company of several soldiers at a bar. One of the soldiers named Mitchell (George Cooper) left his wallet at the crime scene, making him a person of interest. Captain Finlay (Robert Young), the cop in charge of the investigation, questions Sergeant Keeley (Robert Mitchum), who knows Mitchell. Keeley doubts Mitchell's capable of killing anyone, and tries to find him on his own, stalling the police for as long as possible until he can get Mitchell's story. He eventually does track down Mitchell, and get his account of the night of the murder - what he can remember of it, at least, given how drunk he was. Still, Keeley is convinced of Mitchell's innocence, and he and Finlay both zero in on another soldier who was present at the crime scene - Montgomery (Robert Ryan), who has a history of making bigoted comments, including towards Jews. In the absence of any evidence besides a motive, Finlay and Keeley work together to determine the truth about Mitchell's innocence and Montgomery's guilt.