控方证人是一部剧情,犯罪,悬疑片，伦敦著名刑案辩护律师韦菲爵士（查尔斯•劳顿 Charles Laughton 饰）接受了心脏病治疗，但是身体依旧虚弱，第一天回家休养，护士一直严厉监督他服药，并杜绝烟酒。管家为了便于上楼，还专门为他修了电梯。但是，种种关心照顾，对于这位桀骜不驯、牙尖嘴利的大律师根本不起作用，反倒是一纸诉状令他倍感兴奋。律师梅休和当事人沃尔（泰隆•鲍华 Tyrone Power饰）登门拜访，请他出山打官司。原来，沃尔结识了富婆，两人相见甚欢，虽然仆人对他发明的打蛋器充满鄙夷，但是富婆却对他充满爱意，甚至为他修改了遗嘱，把8万英镑留给了他。然而，富婆却惨遭毒手。于是，沃尔成为警方的头号嫌疑犯。他的唯一证人是妻子克里斯汀（玛琳•黛德丽 Marlene Dietrich饰），然而后者登门时的冷漠与淡定，令韦菲爵士怀疑这其中另有隐情。在扑朔迷离的案件背后，隐藏着一个个环环相扣、不可告人的秘密…… 本片改编自阿加莎•克里斯蒂同名小说。©豆瓣
It's Britain, 1953. Upon his return to work following a heart attack, irrepressible barrister Sir Wilfrid Robarts, known as a barrister for the hopeless, takes on a murder case, much to the exasperation of his medical team, led by his overly regulated private nurse, Miss Plimsoll, who tries her hardest to ensure that he not return to his hard living ways - including excessive cigar smoking and drinking - while he takes his medication and gets his much needed rest. That case is defending American war veteran Leonard Vole, a poor, out of work, struggling inventor who is accused of murdering his fifty-six year old lonely and wealthy widowed acquaintance, Emily French. The initial evidence is circumstantial but points to Leonard as the murderer. Despite being happily married to East German former beer hall performer Christine Vole, he fostered that friendship with Mrs. French in the hopes that she would finance one of his many inventions to the tune of a few hundred pounds. It thus does not help his case when it is learned that Mrs. French changed her will prior to her murder with Leonard being the primary beneficiary of a £80,000 estate. Leonard states that he knew nothing about the will. Christine is apparently the only alibi Leonard has to his whereabouts at the time of the murder. The usual methods Sir Wilfrid uses to test his clients' guilt or innocence leads to him believing that Leonard is indeed innocent. As the trial progresses, the prosecution calls a surprise witness, one that could place a nail in the coffin of Sir Wilfrid's planned line of defense. As Sir Wilfrid gets deeper and deeper into the case, something doesn't quite sit right with him, although he doesn't know what it is. The primary questions become how far Sir Wilfrid will go to obtain evidence to acquit Leonard, and if he will ever discover why he feels that there is something odd about the case.