On a night flight, three men steal diamonds from a millionaire aboard an airliner in mid-air. When Police Superintendent Benting H.G. Stoker tries to intervene, passenger Jack Drake Tom Walls knocks him out to prevent him from being shot. The thieves force the pilot to land so they can dump the passengers, but they discover the diamonds have already vanished, taken by someone else—Drake.
Drake is a modern-day Robin Hood figure, quietly gesturing toward a broader mission. He donates the proceeds of his latest robbery to fund the stalled construction of the New Social Institute, and even writes a book, Crackerjack: The true story of my exploits., which becomes a bestseller. The story travels far, catching the attention of people at Scotland Yard and of Baroness Von Haltz Lilli Palmer, who can’t help but wonder if the adventures are factual or fiction. The baroness confides in her maid Annie Ethel Griffies that certain passages ring true, recalling Drake, the man who once broke her heart in Berlin.
By sheer coincidence, the baroness ends up staying at the same hotel as Drake. He goes to see her, yet she does not forgive him for leaving without a word. He explains that a sudden departure forced his hand, but she remains wary. Meanwhile, Drake directs his secretary Burdge Charles Heslop to send a £10,000 donation to Buckingham Hospital for a new wing, even though Burdge warns him that the bank is overdrawn. Drake reminds him that the riches of Mrs. Humbold Muriel George will cover the expense. The Humbolds host a masquerade ball that night, and the baroness will be in attendance.
At the ball, a troupe called the Four Gangsters is replaced by a group of real gangsters—the same crew from the aeroplane job. Sculpie Noel Madison, their leader, kills an unarmed man who resists, but he is furious to learn that the pearls he stole from Mrs. Humbold are fake; Drake still holds the genuine ones. An advertisement in the newspaper invites Crackerjack to help someone in trouble, drawing Drake to a meeting with the baroness, though he speaks to her indirectly rather than face to face. She reveals that the letters in question are used as blackmail by Hambro Golding Leon M. Lion, who is also part of Sculpie’s gang. The baroness explains that these letters keep her from marrying.
Crackerjack’s name intrigues the baroness enough to seek his aid, and she explains that Golding claimed Crackerjack would attempt to burgle his safe for the letters. Sculpie, delighted by the setup, overhears the baroness returning for a forgotten handbag and catches wind of Crackerjack’s fate. Suspecting that Drake is Crackerjack, she arranges a dinner to confront him, but Drake fails to show up. Burdge escorts her to Golding’s place, where Drake is eventually captured, though he manages to turn the tables on the gang and even coordinates a police raid.
In the end, Drake escapes into the night and flies away with the baroness, their fates intertwined as they head toward a marriage. The caper blends clever con games, high-stakes theft, and a complex web of loyalties, all driven by Drake’s audacious blend of generosity and cunning, with the hotel, the masquerade, and the grand poker of risk leaving a pulse on every character involved.
