In this compelling investigation, author Michael Smith explores the critical moment in a spy's life: that split-second decision to embrace a double life; to cheat and hide and hurt; to risk disgrace – even death – without any guarantee of being rewarded or even recognised.

Each chapter centres on a different spy, following the path they took that lead, finally, to the point of no return. Were they propelled by personal convictions? Blackmailed and left without a choice? Too desperate for money to think about the consequences?

Through in-depth insider knowledge, Michael Smith also uncovers new and unknown cases, including ISIS, President Trump's links with Russia and Edward Snowden's role as a whistleblower, to offer compelling psychological portraits of these men and women, homing unerringly on the fault-lines and shady corners of their characters, their weaknesses and their strengths, the lies they tell other people, and the lies they always end up telling themselves.