Where does the man who fooled the gangsters intend to send the money from the pearls?
Three men rob a millionaire of diamonds aboard an airliner in flight. When Police Superintendent Benting tries to intervene, Jack Drake, another passenger, knocks him out to save him from being shot. The thieves force the pilot to land so they can dump the passengers. However, the men find the diamonds have already been stolen by someone else (Drake). 
Drake is a sort of modern-day Robin Hood. He donates the proceeds of his latest robbery to fund the stalled construction of the "New Social Institute". He even writes a book, "Crackerjack": The true story of my exploits., which becomes a bestseller. Everybody is reading it, including the people at Scotland Yard and Baroness Von Haltz, and wondering if it is fact or fiction. The baroness tells her maid Annie that certain passages somehow remind her of Drake, who broke her heart. 
By coincidence, she is residing in the same hotel as Drake. He goes to see her, but she does not forgive him for leaving her without a word in Berlin. He explains that he was forced to leave suddenly, but she is not mollified.
Meanwhile, Drake instructs Burdge, his secretary, to send a cheque for £10,000 to the Buckingham Hospital for a new wing, even though Burdge informs him he is overdrawn at the bank. Drake tells him that the wealthy Mrs. Humbold's pearls will provide ample funds. The Humbolds are hosting a masquerade ball that night, and the baroness will be there.
At the ball, part of the entertainment is a group called the "Four Gangsters", who have been tied up and replaced by a gang of real gangsters, the same thieves from the aeroplane caper. Sculpie, their leader, kills an unarmed man who foolishly tries to resist. Afterward, however, Sculpie is furious to learn that the pearls he took from Mrs. Humbold are fakes. Once again, Drake has the real ones.
Buckingham Hospital