Art restorer, Gabriel Allon, who also works part-time for 'The Office', a semi-official Israeli intelligence agency, accepts an assignment from an anonymous Zurich banker.

He is interrogated by Gerhardt Peterson, of Switzerland's internal security department, who accuses him of the murder of the deceased banker, Augustus Rolfe.

Although Anna staunchly defends the provenance of those valuable paintings, Gabriel suspects that they were underhandedly acquired during World War II.

It is revealed that Peterson takes orders from the 'Council of Rütli', a secretive elite group of Swiss businessmen and bankers determined to protect the reputation of Switzerland and its (often stolen) riches.

Keller began his career in the SAS, and actually visited Israel, where he studied combat and intelligence techniques from members of the Office, including Allon.

He was posted as 'missing believed killed' after a mission in Iraq, but in fact survived and became a freelance assassin, reaping a comfortable lifestyle.

He lives in a Corsican village, becoming something of an adopted kinsman to the Orsati family and its self-proclaimed role as the arbitrators of justice.

He warns that Swiss law protects its collectors who purportedly bought the art “in good faith” and have owned it for five years.

Isherwood refers Gabriel to the exiled Swiss Emil Jacobi, a historian, writer, and 'whistle blower' who contests the morality of Switzerland's acquisition and ownership of “looted” art.

Jacobi relates that it was not uncommon for Nazi leaders to reward such informants with valuable property, including art.

Gabriel returns to Zurich and discovers photographs of Rolfe with Nazi leaders Heinrich Himmler, Hermann Göring, and Adolf Hitler.

It emerges that Peterson had coordinated both Gabriel and Anna's planned murders, but Keller decided that he was killing for the wrong team.

Gabriel determines to ask Gessler to exchange the confiscated art in return for its monetary value, but Peterson expresses scepticism that a wealthy man could be bribed with more money.

After sustained beatings, Gessler takes him on a tour of his own private art collection—a vast museum housing hundreds of great paintings.

He calls upon the Orsati family's long-standing tradition of honour killing and states that justice demands the life of Otto Gessler, not Gabriel or Anna.