Synopsis
Outside London, American merchant marine officer David Martens strikes up a conversation with Sally Meadows at a cemetery where he is visiting the grave of his pilot brother Jack, killed two years earlier. When David learns Sally is an assistant designer for modeling agency Beauchamp and Co., he reveals that he is searching for model Diane Leigh, Jack's former fiancée, and Sally reveals that Diane works for her company. David explains that he is in London for only one day and asks Sally for a date that evening, then arranges to come to the shop to meet Diane later. That afternoon, Sally joins her sister Annabel, a model at the shop, to prepare for a run-through of the show overseen by Kingsley Beauchamp, the company's credited stylist. Although Beauchamp is well known in fashion circles, his longtime lover, Madame Madeleine Dupont, is secretly the company's actual designer and manager who backs him financially. After the rehearsal Madeleine expresses concern over Beauchamp and Diane's carelessness with a set of diamonds on loan to them for the show. The jewels are guarded by the diamond company's representative, Mr. Bullock, who places them in a locked safe, to which he holds the only key. David arrives at the shop and Diane asks him to meet her at Club Jamaica that evening. A few hours later, David picks up Sally for their date and meets Annabel and her photographer boyfriend, George. The two couples go to Club Jamaica where the women are startled to see Diane wearing the premier dress from the Beauchamp collection. Meanwhile, Beauchamp's chauffeur Costard and burglar Podd sneak into the shop and break open the safe containing the jewels. At the club, Diane asks David to dance with her and afterward in private returns an heirloom ruby bracelet that David's mother had sent her upon her engagement to Jack. Concerned about getting the designer gown back to the shop safely, Diane decides to leave. Unknown to the others, another model, Tessa, telephones Beauchamp to inform him that Diane is wearing the gown and returning to the shop. A little later, as David leaves the club, he tells Sally that his ship's departure has been postponed and invites her to lunch the next day. At the same time, Diane arrives back at the shop and, hearing strange noises from the upstairs office, comes upon Costard. Frightened, she turns to flee, but the chauffeur flings a knife into her back. Diane collapses in the shop window just as David, walking back to his hotel, passes by. Horrified, David pounds on the shop's front door, unaware that Beauchamp has witnessed the incident. At the rear of the shop, Beauchamp intercepts Costard and Podd, with whom he is in cahoots, as they prepare to flee with the diamonds. Beauchamp orders Costard to take Diane, dispose of the dress, then dump her body. David succeeds in breaking into the shop, but Costard knocks him out before he sees Beauchamp or Podd. At Beauchamp's instruction, Costard places David in Beauchamp's car and drives it into a wall, then removes Diane in the company van. Beauchamp then reports the car as stolen. The next day, David revives in the hospital and is questioned by police inspector Duncan and Sgt. Sam Anderson. David informs them of Diane's murder, but Duncan reveals there is no body, then asks him about the stolen car and diamonds. When Duncan asks David to identify the ruby bracelet found in his pocket, David realizes he is under suspicion for the theft. Learning of David's accident, Sally visits him later and although disturbed by his news of Diane's murder, believes he is innocent. Back at the shop, Beauchamp and Madeleine pack for the upcoming fashion show in Amsterdam. Afterward, Beauchamp meets with Costard to give him costume jewelry that Podd is to reset with the stolen diamonds in order to transport them out of the country. When David insists he must locate Costard, Sally has Annabel bring some of George's clothes and, while the sisters distract Anderson, David slips out of the hospital. At the shop a little later, Sally answers an unusual call reporting that Beauchamp's cat has been found some miles away at a river lock. Puzzled, Sally telephones David at her flat and, on a hunch, he takes a cab out to the river. When Madeleine reports the cat's discovery to Beauchamp he angrily
confronts Costard, pointing out that the cat must have been in the van when the driver took Diane's body away. David retrieves the cat and learns from the lock-keeper that he heard a loud splashing sound the night before, but found the cat dry. Just then, David sees Costard drive up in a van, but when the chauffeur spots him, he drives away. David follows and moments later the lock-keeper stumbles upon Diane's body and reports his discovery to the police. Sally is summoned for questioning by Duncan as David goes to Beauchamp to tell him that he is certain Costard murdered Diane. After David departs, Costard appears and angrily insists that the merchant marine must be killed. Beauchamp agrees and advises Costard to make the murder appear to be a suicide. Knowing David is likely staying with Sally, Beauchamp telephones her flat, but Annabel reveals her sister has gone to the police for questioning. To lure Annabel out of the apartment, Beauchamp invites her for cocktails to offer her Diane's spot in the show. When David returns to Sally's apartment by the back entrance, he is knocked out by the waiting Costard, who then turns on the gas. At Beauchamp's apartment that afternoon, Madeleine confronts him with her suspicions that he is involved in the murder and theft and demands that he sign over the business to her or she will go to the police. Upon returning home, Sally is drawn by the anxious cat to the back entrance where she rescues the unconscious David. The next morning, aware that the flat is under surveillance by the police and with only a few hours before Beauchamp's chartered flight to Amsterdam departs, Sally, Annabel and George devise a ruse to help David slip out of the building to confront Costard. David goes to Costard's home where he finds Mrs. Costard wearing the Beauchamp designer gown worn by Diana. The woman admits knowing nothing about her husband's actions, only that he asked her to burn the dress. When Beauchamp telephones, David pretends to be Costard and learns the diamonds are hidden in the costume jewelry. David hurries to the airport to warn the customs officials of the robbery and is startled to find Duncan, Anderson and Bullock there. Confronting Beauchamp and his crowd, Duncan ignores the costume jewelry and instead examines Costard's driving cap, where he finds a hidden stash of jewels. When Bullock states that the stones are paste, Costard furiously realizes Podd intended to double-cross him. Seeing a figure in a wheelchair heading for the exit, David intercepts the chair and uncovers a disguised Podd, who is carrying the real diamonds. Duncan then places Beauchamp, Costard and Podd under arrest and, returning the ruby bracelet to David, assures him that he will clear up any difficulties with the authorities. Delighted, Sally and David wonder hopefully about their future and share a kiss.
