Berlin Game by Len Deighton
The novel revolves around a British intelligence officer stationed in Cold War-era Berlin, who is tasked with managing a critical network of spies and informants behind the Iron Curtain. When he receives alarming intelligence suggesting that there is a mole within his own department, he must navigate a treacherous landscape of deception and betrayal to uncover the traitor. As he delves deeper into the investigation, he finds himself entangled in a dangerous game of espionage, where trust is scarce and the stakes are life or death. The officer's personal and professional lives collide, forcing him to confront the harsh realities of his secretive world and the toll it takes on his relationships and his conscience.