Daniel Corban reported his wife Elizabeth was missing. They had been married three months, and after a quarrel, she disappeared. Father Maximin of the parish St. Jean stops by to deliver a holy picture to Elizabeth as a thanks for her generous donation to the church. The priest reports he saw a young woman at afternoon prayers whom he recognized as Elizabeth, and just then, she comes into the house, eager to reunite with her husband.

Daniel, however, insists that the woman is not his wife. She blames his nerves and depression for his memory loss, while Daniel accuses her of trying to impersonate his wife so as to get to his money. Daniel calls up the police inspector to straighten the mess out. Elizabeth's uncle is a millionaire and in poor health, and Elizabeth is expected to inherit everything from him. Daniel sees this as a motive for a strange woman to impersonate his wife, and claims that the priest and the strange woman are plotting to get to his wife's wealth.

The inspector questions both 'Elizabeth' and the priest, but all their explanations sound logical, and Daniel becomes more and more agitated. He questions the woman about their lives, and she answers each question correctly. Daniel states he is fearful for his life because a telegram dated three weeks previously confirms that Elizabeth's millionaire uncle has died.

The inspector leaves, and Daniel walks into the room and sees the woman claiming to be his wife slip some pills into his whiskey. Daniel deliberately gives the glass to Father Maximin, who drinks it, and collapses. Daniel runs to get the police, and when Daniel and the inspector return to the chalet, the priest is nowhere to be found. The inspector confides to Daniel that he is suspicious of the woman, and asks Daniel to play along until further evidence can be found.

A wandering artist named Merluche stops by, and recognizes Daniel from their honeymoon stay in Juan les Pins. Daniel promises the artist a thousand francs if he will draw a picture of Elizabeth from memory so he can prove to the inspector that the woman claiming to be his wife is an imposter. She and Father Maximin show up, and after finding out what the artist plans to do, she shoots Merluche. She tosses the gun to Daniel, who reflexively catches it just as the inspector comes in.

Father Maximin and 'Elizabeth' both insist that Daniel shot the man, while Daniel claims the opposite. The police inspector brings in a witness, a nurse who had treated Elizabeth, and she acknowledges that the woman with Father Maximin is indeed Elizabeth. Father Maximin places an envelope with money into the nurse's purse on her way out, and Daniel can't seem to convince the inspector that the nurse was bribed to lie. Merluche is apparently not dead, but in the operating room, and is now the only witness who can corroborate Daniel's claim.

After the inspector leaves, 'Elizabeth' calmly admits she's after the money. The furious nurse returns, claiming Maximin and Elizabeth have cheated her. She says she will back Daniel up if he pays her five thousand francs, and Daniel gives her his wife's ring to write a statement for the police. 'Elizabeth' shows up, and hands the nurse even more cash, and the nurse takes the highest bidder and tears up the statement. 'Elizabeth' drops the final bomb when she tells Daniel that Merluche died. Daniel is to be committed to a mental hospital, and 'Elizabeth' makes arrangements to visit her solicitor to claim her inheritance. The inspector arrives and tells the group that Merluche had survived the surgery, but died shortly thereafter under mysterious circumstances. Daniel initially accuses Maximin of killing Merluche, but then claims to have done it himself to try to convince the inspector to arrest him so that 'Elizabeth' and Maximin can't put him away.

The inspector proposes that both 'Elizabeth' and Daniel submit to being injected with sodium pentothal to see which party is telling the truth, and both agree. In horror, Daniel sees Elizabeth and Maximin switch syringes, and when the inspector returns from an urgent phone call, claims that the two are trying to kill him. Daniel fights desperately while the inspector tries to inject him. Daniel now claims the inspector has masterminded the whole plot, and accuses the inspector of killing Elizabeth. The inspector points out that unless they find Elizabeth Corban's body, Daniel can never prove the woman is not his wife.

Now over the edge, Daniel babbles that his wife will be found in the Chamois gorge, and too late realizes he has given himself away. The inspector tells him that the body had actually been found three days after Daniel had reported her missing and the nurse had identified her as Elizabeth. The inspector tells Daniel he could have arrested him any time, but wanted to get a confession, so a sting operation was set up. The inspector, Chief Inspector Tarquay (Maximin), Mademoiselle Stephanie (Elizabeth), the nurse and Merluthe had all played their part in setting a trap for a lonely man.