Based on J. B. Priestley's play, three partners and their two wives and girl-friend discuss who stole the money and why their partner committed suicide.
Ann Beale (Virginia Bruce) has breakfast with author Maude Mockridge (Doris Lloyd). Ann's friend Charles Stanton (Melvyn Douglas) plans a surprise anniversary party for Robert Chatfield (Conrad Nagel) and his wife Freda Chatfield (Erin O'Brien-Moore). Ann brings in an agreement with Mockridge. Charles, Robert, and Gordon (Henry Wadsworth) can't find a bond in the safe. Robert calls Martin, because they have the four keys. Charles calls for Martin and finds he shot himself. The court verdict is suicide.
At a dinner party Mockridge urges Charles to marry Ann. Robert shoots a gun at a flower pot. Charles says truth is dangerous like driving fast around a corner. Ann says only half-truths are dangerous. A radio tube burns out; so they talk. Ann says Freda's music box was Martin's. Freda admits she gave it to him. Freda was the last to see Martin except for Ann. Mockridge leaves. Robert asks Freda and Ann why they hid this. Ann went to see Martin about the money and asks Robert if he took it. Betty (Betty Furness) leaves with her husband Gordon. Freda says Ann is in love with Robert and that she and Robert are not happy. Ann says Martin did not take the money. Robert and Freda suspect that Charles took it. Robert calls Charles and Gordon to come back. Charles is accused and admits he took it. Charles implies that Freda was the reason for Martin's suicide, and she admits to Robert that she loved Martin for a long time, saying it was hopeless and crying. Betty comes back and asks why Martin killed himself. Ann says she shot him, and Charles says it was an accident. Ann tells what happened.
Ann calls on Martin (Ian Keith) and asks him who took the money. Martin says Robert is a thief and that Ann has a crush on Robert. Martin laughs at Ann for lacking passion and tells her to take the gun from him. He holds her, and the gun goes off as she tries to get away.
Charles and Robert don't blame Ann. Charles had picked up a piece of her dress. That night Ann went to Charles' place but saw Betty there. Betty says that Charles wouldn't let her stay and that her marriage was a mistake. Betty says that Charles paid her gambling debt with the money. Robert is disillusioned. Charles calls Robert a fool. Robert tells Charles to get out, and Gordon asks Charles to resign. Charles leaves. Then Gordon and Betty leave. Ann tells Robert to live without illusions. Robert rushes out and shoots himself.
A title says this might have happened, but what did happen was this: a new radio tube provided music and prevented conversation. Robert toasts Mockridge's new book, The Sleeping Dog. Charles proposes again to Ann, and she surprises him by accepting.
This drama suggests that people know less about their closest friends and associates because of the distractions of mass media. An intricate mystery and the truth about their hidden relationships would have been revealed if they didn't listen to the radio.