The novel begins at an American checkpoint on the Berlin Wall, soon after the barrier’s construction in 1961. British secret service agent Alec Leamas has been waiting for nine hours for his agent Karl Riemeck to cross from East Berlin into West Berlin. Alec Leamas tells his impatient American minder—a CIA agent—that he must keep waiting, because his agent is on the run from Mundt. The American wonders aloud how Mundt knows that Riemeck is spying for the British, and Leamas rudely tells him to shut up.
The start of the novel introduces us to Alec Leamas in his normal state of mind: on edge and acting rudely as he waits to see if his agent will escape out of East Germany. Leamas clearly finds this a stressful situation, but at this point, it is unclear whether he is worried about Riemeck’s safety out of loyalty to the personal relationship they have developed or merely because Riemeck is important to Leamas’s work.
Leamas watches as a car crosses the checkpoint, then goes out to talk to the occupant of the car, a woman named Elvira. She tells Leamas that Riemeck escaped arrest in East Berlin and will try to cross through the Berlin Wall tonight at this checkpoint. Leamas is angry that Riemeck has told Elvira so much; she says that Riemeck trusts her and tells her everything.
Leamas buys into the belief that the spy must avoid human connections that could compromise the mission, and he looks down on Riemeck for compromising their work together by sharing information with a third-party, even one he trusts and loves.
Leamas reenters the checkpoint hut and apologizes for having been rude, giving some whiskey to two West German policemen who are working there. The CIA agent has left. Leamas asks whether they can shoot to protect an agent on the run, and they say that they’ve been instructed never to shoot unless the “Vopos” (East German police officers) shoot into the American sector for fear that firing into the East will start a war. Leamas explains that he is awaiting an agent that Mundt’s men are pursuing. They tell him there are still places where a person can climb over the Berlin Wall, but Leamas says that his man will talk his way out and ride over on a bicycle.
Seeing the two German police officers who have stayed on the job instead of leaving impatiently, Leamas has an impulse to reach out to these men and show his solidarity with those who place their jobs above all else, showing loyalty to their duties rather than their personal lives, so he gives them some whisky. Alcohol is clearly an important crutch used by agents to get through stressful, alienating experiences like waiting to see if Riemeck will make it to safety.
As Leamas waits, he looks out at the Berlin Wall, whose ugly design reminds him of a concentration camp seen during World War II. He thinks back on the moment, some months before, when he first discovered that Riemeck had confided in Elvira. Riemeck had had a huge success and Control had come to Berlin to meet him. At a bar, afterwards Riemeck had introduced Leamas to his mistress Elvira. Leamas then discovered that Riemeck had shared a lot of information with Elvira, and Leamas trusted him less from then on, only telling him what Riemeck absolutely to know. Now, having heard from Elvira that she knows everything, Leamas swears to himself never to trust an agent again.
The Berlin Wall is a symbol of the high tensions between the two sides in the Cold War, and for Leamas it evokes memories of the war he lived through. Leamas sees the secrecy of his work as an important way to prevent the outbreak of another war by keeping the Communists too weak to dare to challenge the West. He sees Riemeck’s disclosures to Elvira as creating new and unnecessary weaknesses for the Western side, and he believes that he would never compromise his important mission in this way.
Leamas, who offered Elvira a place to stay at his flat and told her he would bring Riemeck later, calls to tell his landlady to expect guests that night. One of the policemen interrupts him, saying a man on a bicycle is crossing. Leamas sees that Riemeck has passed through the document check on the Eastern side and now must go through currency and Customs. Riemeck makes it through these checks, then begins to bike towards the line between the Berlin Wall between East and West. At that moment, the searchlights go on and a siren begins to wail. Taking care not to shoot into the Western sector, an East German sentry shoots Riemeck, who falls from his bicycle. Leamas hopes to himself that Riemeck is dead.
The Communists suspect Riemeck of spying for the British, and so they kill him, which reflects an ideology that allows for the summary killing of individuals. Leamas hopes that Riemeck is dead for two reasons. First, he knows that if he is not, Riemeck will be interrogated and tortured. For Riemeck’s sake, Leamas hopes this won’t occur, and for the sake of the West, Leamas hopes that Riemeck is dead and cannot be forced to reveal the secrets he knows to the Communists.