The Ipcress File by Len Deighton

A high-ranking scientist has been kidnapped, and a secret British intelligence agency has just recruited Deighton’s iconic unnamed protagonist—later christened Harry Palmer—to find out why. His search begins in a grimy Soho club and brings him to the other side of the world. When he ends up amongst the Soviets in Beirut, what seemed a straightforward mission turns into something far more sinister.

With its sardonic, cool, working-class hero, Len Deighton’s sensational debut and first bestseller The IPCRESS File broke the mold of thriller writing and became the defining novel of 1960s London.