A 1951 British film noir starring Robert Preston. Preston is a Canadian living in Merry ol' England, married w/a young one on the way. He served w/the Brits during the war as a cryptologist (code breaker) & still toils in that craft as a career. Tragedy strikes when one night while out on a walk w/his wife, played by Elizabeth Sellars, near their home a speeding car strikes & kills her but not before in desperation Preston grabs hold of the driver begging him & his companion for help before they flee away. Preston then sets out on a road for revenge by corralling some of his old running mates from the service to provide him w/info & tools to find the errant killers (we learn they were racing from the scene of another murder before hitting Sellars) but after Preston dispatches the driver (he runs him over w/his car) a perverse game is enacted as he leaves a note w/an encrypted code which the investigating officer brings to his office to decode. As the narrative runs down, Preston sets his sights on the driver's companion who has been taken into protective custody w/the detective putting together all the pieces to figure out who the culprit is. Preston is fantastic here as man of action working through his anguish where his goal will not bring him the satisfaction he thinks he'll get.