Reilly’s misdeeds, however, did catch up to him. After his narrow escape from Moscow, he was working with an underground anti-Communist organization called “The Trust” in Finland. The leadership invited him to meet them in Moscow and offered to smuggle him in. What he didn’t know was that the Soviets started “The Trust” as a front to capture dissidents, and Reilly walked into a trap. He was arrested.
He was held in the notorious Lubyanka prison and interrogated, but not very hard, apparently. He appeared willing to betray anyone to save himself and offered vital information about British and American spies. He even wrote to Cheka, the Soviet Security Agency to turn informant. They had a different idea.
He was taken to a forest outside of Moscow in November 1925 and executed. Whether or not the Ace of Spies was really going to spill or not, was a matter of debate. When they went into his cell after his death, they found cigarette papers with written notes, stuffed into cracks in the wall. He was documenting Soviet interrogation techniques, which he was hoping to sell to the highest bidder upon his release.
No one knows what he was planning to tell the Soviets, but given his track record, it might not have been in the best interests of the Queen. Not that he cared.
He was a badass spy.