Based on a play by Jeffrey Dell, a bank clerk, desperate for money, murders his nephew and finds some relief when his wife learns of his guilt.
In a prolog a man wants to rent a house, where a murder occurred. Annie Marble (Dorothy Peterson) and her daughter Winnie Marble (Maureen O'Sullivan) ask William Marble (Charles Laughton) for money for Winnie's shorthand course, and the butcher demands he pay his bill. Will is a clerk in a bank; but his boss tells him he must pay a debt by Tuesday or he will be dismissed. Will tells Annie that he ordered cyanide poison for his photography. Will's nephew Jim Medland (Ray Milland) arrives and says his parents died. Wills sees that Jim has money. Will gives Jim a tip to buy francs on margin and asks for 10% commission; but Jim firmly refuses. Will tells Jim that he must have 100 pounds, but Jim says no and regrets coming. Will offers Jim a drink and puts poison in it. As Jim drinks, Will drops his glass.
In the morning Annie asks Bill about his dirty clothes, but he gives her money to pay a bill and looks at the grave in the yard. Hammond tries to sell Will property, but Bill says they will never move. Will is congratulated at the exchange and tells Annie and Winnie that he made 30,000 pounds. Bill plans to buy their home and lets Annie and Winnie go on a vacation. Annie asks Bill to tell him what he did and says she knows, assuming he stole money. Annie and Winnie leave in a taxi. Will reads books on crime and cyanide poison. Rita Collins (Verree Teasdale) calls on Will and admires his furniture. Will says he is lonely and kisses her. On their last evening Rita asks Will for 300 pounds. Winnie and Annie come home early, and Winnie sees Rita leaving. Annie tells Will that Jim Medland is missing. Winnie asks Annie why Will gets so upset and notices he reads about cyanide. Annie realizes what happened and cries.
Will tells Annie that money has not done them much good; but he admits it is more like it was since she knows. Winnie comes in, and Annie objects to her smoking. Will says that Winnie is a snob, and they quarrel, causing Winnie to tell Annie about Rita. Annie runs out in the rain after Winnie. Annie asks Will about Rita, but he denies knowing her. Will cares for ill Annie. Rita calls on Will and demands 500 pounds. Annie hears and gets up to see Will writing her a check. Rita leaves, and the doctor comes in. The doctor tells Will that Annie just died from poison and after investigating asks him why he killed her. Will laughs. Winnie visits Will in prison after his last meal. Will says he didn't do it, but he is at peace. Winnie embraces Will and says she will pray for him. She leaves, and Will calls to Annie.
Will's conscience is relieved by his deferred punishment after his wife's apparent suicide. This drama ably shows some of the bad consequences of a horrible crime even though Will seemed to be getting away with it.