For international operative Gabriel Allon and his wife, Chiara, it was supposed to be the start of a pleasant weekend in London—but a pair of deadly bombings in Paris and Copenhagen have just occurred, and while walking toward Covent Garden, Gabriel notices a man he believes is about to carry out a third attack. Before Gabriel can draw his weapon, he is knocked to the pavement and can only watch as the nightmare unfolds.

Haunted by his failure to stop the massacre of innocents, Gabriel returns to his isolated cottage in Cornwall until a summons brings him to Washington, and he is drawn into a confrontation with the new face of global terror. At the centre of the threat is an American born cleric in Yemen to whom Allah has granted "a beautiful and seductive tongue." A gifted deceiver, who was once a paid CIA asset, the mastermind is plotting a new wave of attacks.

Gabriel and his team devise a daring plan to destroy the network of death from the inside, a gambit fraught with risk, both personal and professional, and to succeed, Gabriel must reach into his violent past.

Set against the disparate worlds of art and intelligence, Portrait of a Spy is a breathtaking portrait of courage in the face of unspeakable evil.