Hambledon is back in Berlin snatching secrets and liquidating Nazis, and doing so through the courtesy extended to him as an honored guest of the unsuspecting Reich.

News that Hambledon is killed in a chemical explosion spreads gloom throughout the British Foreign Office and Military Intelligence. He had been sent to Switzerland to investigate a new explosive being developed by Professor Ulseth, a famous German chemist. Both Hambledon and the professor had apparently gone up in the blast. Then from British agents inside Germany come reports that a Professor Ulseth is in Berlin, alive and doing well under the care of the Nazis—but the Herr Professor’s fingerprints are those of Tommy Hambledon.