Kevin Mallory lived a double life - he helped people on his street with yard work, went to church and showed off his dogs. Yet at home he communicated with Chinese agents through social media and sold them US secrets.

Today he is beginning a 20-year prison sentence. His punishment will serve as a warning to others who may be contemplating espionage, say US justice department officials. It also highlights the tense nature of the US-China relationship. China is the number one threat to US interests, according to John Demers, the Assistant Attorney General for National Security, seeking to gain inside information which will shape the way that Beijing policies and its commercial and military activities are perceived on the world stage.

For the Chinese agents, Mallory was a catch. He had worked as a covert CIA officer and held security clearances that gave him access to the nation's most valuable secrets. But by the time they approached him in early 2017 he was working as an independent consultant and struggling to keep up the mortgage payments on his million dollar mansion in Raspberry Falls.

Tara McKelvey tells the story of how Mallory was recruited, deployed and eventually caught by the FBI. It is a very human story of a man who thought he had found an answer to his problems only to find himself trapped. We hear about simple mistakes he made which blew his cover. We hear from his neighbours how he disintegrated under the pressure, to the point of beating the dogs he loved.

After his conviction Mallory told the court that his love for his country had never wavered. That is a hard claim for John Demers to accept; he takes Mallory’s betrayal personally. But psychiatrist David Charney believes him; in the end Mallory’s hatred was never for his country. It was only for himself.

(Photo: A man holding a top secret envelope. Credit: Getty Images)