In Britain, the Treasury Department notices a huge amount of counterfeit British Pound notes flooding the British markets. The British experts determine that the counterfeit paper and the actual printing of the fake currency originate in the United States. The evidence points out to a smuggling ring operating under the cover of a legitimate American airline company based in Britain. Of late, several radio operators working for this airline service have been found murdered in mysterious circumstances. The British Treasury requests help from the United States Treasury Department which sends an undercover Treasury agent to investigate the case. The agent, Mike Conlin, arrives in Britain posing as an efficiency expert for the airline in question with orders to investigate the airline's operations and find ways to improve its service. Under this guise, Mike Conlin arrives in Britain and starts his investigation, while secretly assisted by the Scotland Yard. Soon, however, the bad guys start becoming suspicious of him. His life is in danger.