She was his best kept secret…

Somewhere in a remote village in the Andalusian mountains lives a mysterious French woman who is writing her memoirs. About the man she fell in love with in Beirut years ago, about the child that was born from this love... That woman keeps inside herself the most closely guarded secret of the Russian secret services. Only she knows very well - better than anyone else - the identity of the mole that the Kremlin planted in MI6 long ago. The identity of the child of betrayal, as she calls it.

During the search, Gabriel Allon and his associates get to the most complicated case of the 20th century in the world of secret services. To the greatest betrayal and the greatest traitor, one of the members of the so-called Cambridge Five, who managed to deceive his friends and colleagues for twenty years and worked for the Russians. Although Kim Philby is long dead, his Jewish blood continues to circulate in the veins of the child of treason and he is on his way to more and more power. If anyone can uncover his heir in a complex game of secret services, it is Gabriel Allon.