The longest serving spy for the Secret Intelligence Service (MI6), Ellis came to New York at the beginning of World War II as deputy to William Stephenson at British Security Coordination (BSC) and helped set up for William Donovan the Office of Strategic Services (OSS), what would eventually evolve into the Central Intelligence Agency (CIA). At one point in the 1940s he was considered one of the top three secret agents in MI6, controlling its activities "for half the world."

Ellis allegedly received prior warning of the Japanese attack on Pearl Harbor and, through the conduit of Stephenson, relayed that warning to President Franklin D. Roosevelt. After World War II, Ellis was awarded the the Legion of Merit by President Harry S. Truman.

But in the 1980s espionage writer Chapman Pincher and retired Security Service (MI5) intelligence officer Peter Wright posthumously accused Ellis of having operated as a "triple agent" for Nazi Germany and the Soviet Union.

In 1965, while under interrogation in London, Ellis had allegedly made a confession that he had supplied information to the Nazis prior to the war. The scope of Ellis's purported betrayal was considered even worse than notorious British traitor and double agent Kim Philby, who defected to the Soviet Union in 1963.

However, Pincher's and Wright's accusations against Ellis have never been comprehensively proven. Was Ellis guilty or was an innocent man framed? Did he take the fall for someone else? Or had the intelligence agencies of the United States, the United Kingdom and Australia been fatally compromised by a "super-mole"?

Internationally bestselling author Jesse Fink unravels a gripping real-life international whodunit in this long-overdue biography of the unheralded Dick Ellis, one of the most consequential figures in modern history.