Star-crossed lovers Thérèse (Simone Signoret) and Laurent (Raf Vallone) think they've gotten away with murder after Thérèse's weakling husband "falls" from a speeding train. But when forced to contend with a blackmailer's demands and the mute accusations of Thérèse's mother-in-law (French stage and screen diva Sylvie, in a scene stealing performance), it's only a matter of time before the law, their passion or blind chance trips them up.