Tommy sorts out a pile of detective stories to hone his detective skills bsed on the techniques of fictional counterparts. He has also bought a camera to take photos of footprints and other such evidence that may prove beneficial in solving the case. A young woman named Miss Kingston Bruce visits the office. She lives in Wimbledon with her parents . A night before, a valuable pearl of one of her guests got stolen. Lawrence St Vincent recommended the Blunts to her. She requests Tommy to take up this case and Tommy accepts.
Beresfords arrive at Wimbledon
Colonel Kingston Bruce – The Blunts arrive at Wimbledon and meet Colonel Kingston Bruce. He tells them that Lady Laura Barton, daughter of the late Earl of Carroway, is staying at their house. Among other guests are American couple Mr and Mrs Hamilton Betts. Pearl of Mrs Betts necklace were missing from last night. During a bridge game, clasp of Mrs Betts pearl necklace got broken. She laid it down on an adjacent small white table and forgot to take it upstairs. The next morning, the necklace was still there but the pearl was missing. Apart from the names mentioned, Mr Rennie was also present paying court to Miss Kingston Bruce. Mr. Rennie was not liked by Mr Bruce due to him being a socialist. No one was allowed to leave the house since the loss of pearl was discovered except Miss Bruce who went to Blunts with the case.
Tommy uses his new camera to investigate while Tuppence tactfully questions the servants. They overhear a scrap of conversation between Mrs Kingston Bruce and her daughter about someone hiding a teaspoon in their muff. Later on, Tuppence ferrets out of Lady Laura’s French maid, Elise, that her employer is something of a kleptomaniac. Five times in the past items have gone missing when she has been staying at friends’ houses.
They search Lady Laura’s bedroom and bathroom, momentarily getting stuck in the latter room when Elise cannot open the door. Tommy takes pictures in the bedroom with Elise’s assistance and then quietly tells Tuppence that he has an idea and has to go out to pursue it. In the meantime, she is not to let Lady Laura out of the house.
Tommy returns with Inspector Marriot of Scotland Yard. They go straight back to the bathroom and cut the cake of soap in half. Inside it is the pearl. The reason Elise could not open the door was that she had soap on her hands after depositing the pearl there. Tommy’s photographs included one of the maid and she handled one of the glass slides, leaving her fingerprints. Scotland Yard has identified her from their records as a missing criminal and arrested her. Being the maid of a lady suspected of kleptomania was the best cover she could have had.