the interesting fact that dots in the masthead of the newspaper indicate the different days on which the paper was produced, while his wife spots an advert in the personal column which reads, "I should go three hearts. 12 tricks. Ace of Spades. Necessary to finesse the King." She deduces that this refers to the Three Arts Ball the next evening, "12 tricks" means twelve o'clock midnight and the "Ace of Spades" refers to a somewhat decadent nightclub-cum-eating place in Chelsea where it is fashionable to go to after events like the Three Arts Ball. Curious about "Necessary to finesse the King" and feeling that they need to hone their detective skills, she decides that she and Tommy will go the ball in costume to investigate. They will act as the detectives Tommy McCarty and Dennis Riordan. At the Ace of Spades, the Beresfords sit in a private booth and peer through the door at the various other costumed and masked patrons. The booth next door is soon taken by a woman dressed as Alice's Queen of Hearts and a man outfitted as the gentleman dressed in newspaper. After a while, they hear a cry from the woman followed by the man laughing and then see him leaving. After a few minutes, suspicious, Tuppence makes Tommy follow her into the booth and they find the woman stabbed through the heart. She whispers, "Bingo did it", before she dies. The next day, Inspector Marriot brings Sir Arthur Merivale, the husband of the dead woman, Lady Vere Merivale, round to the Beresford's flat. "Bingo" Hale is known to both of them and he is stunned that his best friend could have killed his wife. Hale had been staying with them and was arrested that morning for murder. Merivale is perplexed as to what the motive could have been and is incensed at the suggestion from Marriot that the two were lovers and that Vere was threatening Hale who was paying attention to a rich American woman. Tuppence shows Sir Arthur the advert from the Daily Leader and the way the two communicated with each other using this device. Before she died, Vere tore off a piece of Bingo's newspaper costume and the police intend to match this up with the discarded costume. Marriot returns to the Beresford's with photographs of the fragment and the section of the costume it came from; he