The story begins in the year 1961 in Berlin, with Alec Leamas waiting for Karl Riemeck to cross from the East part into the West part. Together with a CIA agent, Alec waits for Karl. Alec is worried about Karl who is followed by Mundt, a former Natzist. The reason why Karl is followed by Mundt is because he is a spy working for the British government.
A woman named Elvira comes at the check-point and tells that Karl will cross at the same check-point later that night. After everyone has left, Alec goes inside the barrack where the German soldiers watching the Wall were situated and talked with them about Karl crossing over to the other side. Alec continues to wait for Karl while also thinking about how he can’t trust any of his agents because they keep talking with their friends and lovers.
Alec continues waiting and finally, Karl appears. Unfortunately for him, he is shot before he can cross on the other side.
In the second chapter, Alec returns to London. He feels like a failure because he was defeated by Mundt and Alec feels as if he had disappointed his superiors because his agents have been killed one by one. At the airport, Alec is greeted by a man named Fawley and then taken to see the head of the Secret British Service. Alec meets with Control who asks him about the agents killed in Berlin and about his reaction to all the death around him. Contrary to what Alec was expecting, he is told he must remain a spy for a while longer and help take out Mundt. When Alec expresses his concern about the lack of agents in the field, Control lets him understand that there are still men left on their side in Berlin. Alec is given the task to protect someone of interest for the British Government and is told to speak with two men, George Smiley and Guillam.
Before leaving, Control tells Alec that he must keep his mission a secret and that he must leave the impression that he was disappointed by what he was told.
In the third chapter, Alec gets into his role. He is first demoted and put to work at the Banking department where he quickly begins to act in a hectic manner. He drinks too much and he keeps himself separated from everyone at the bank. He is soon thrown out and he builds the same reputation in his neighborhood, letting everyone understand that he is unstable and out of money. Soon enough, everyone stays clear of Alec and begin spreading rumors about him on their own.
After Alec leaves his job at the Banking Department, he is moved to a new job at the Library for Psychic Research where he makes himself hated by the woman he works under, Miss Crail, almost immediately. Alec becomes friends with a woman named Liz who begins to invite him over to her house. Liz understands that Alec has some secrets and she tells him one night that she is a Communist. Then Alec leaves her house, he sees a man lurking around but he decides to ignore him.
After a week, Alec stops coming to work and Liz goes to check on him. She finds him sick and Liz begins to take care of him. Alec changes as well, becoming more affectionate towards Liz. This all stops one night when Liz comes to the apartment and sees that some of Alec’s things went missing. Alec then kisses Liz and tells her to not follow him.
The next day, Alec injures a store clerk and the incident is mentioned in the papers. After the incident, Alec spends three months in prison. When he gets out, he is stopped by a man named Ashe and Alec suspects that the man may have been following him. Alec goes to Control where he reports everything that has happened in the last months and when Control mentions Liz, Alec insists that she must be left alone. Alec asks about Smiley and it is implied that he no longer wanted to do the spy work and accept the sacrifices it implies. Before leaving, he insists one more time that Liz must be kept out if everything.
The next day, Alec meets with Ashe and they eat lunch together. Ashe tries to find wather Alec was a spy during his time in Berlin but Alec remains ambiguous in his answer. Ashe brings Alec to his apartment and then leaves to buy groceries. While Ashe is out, Alec makes a call about the man he is supposed to meet that night, someone named Sam Kiever.
When Ashe returns, he is accompanied by Sam Kiever and the three go out to have dinner. During dinner, Alec tells Ashe angrily that he knows that he was being followed and Sam tells Ashe to go away, insisting that he will deal with Alec.
Sam tells Alec that the Worker State or the U.S.S.R. will pay him a great deal of money to give away information about the Secret Service he is working for. To do this, Alec must travel to Holland where he will meet with the ‘’client’’ with whom he will have to carry a conversation. Alec is then given a fake passport and is told to be ready the next day to leave for Holland.
The next day, Alec is given a luggage as not to attract any attention and the airport he is told his passeport will expire in a month. Thus, Alec knows that he will depend on Kiever to return home. Once more, Alec notices a man following his every move.
Alec and Kiever enter a car and they are taken to a hotel where Alec is left in the care of a man named Peters. Alec is then taken to a back room where he is told he will be interrogated for three days before he can be determined to be safe. Alec tries to rush things, telling Peters that he is in danger because he betrayed his country.
Alec then commence to talk about his service. Alec became a soldier during the Second World War and because he knew Dutch, he was sent to Holland. There he was recruited into the Secret Service because he spoke the language. Because the situation in Holland became tense, he was sent to Norway. When the war ended, Alec tried to follow other career paths but soon found that he was unsuited to do anything so he became a spy once more. However, because his service was interrupted, Alec’s pension was reduced.
After a few years of working back for the Secret Service, Alec was sent to Berlin where he was put in charge. Alec then talks about the agents he had and how all of them were killed. Surprisingly, Peters knew about some of them and even revealed that he was present when some of them were killed. Alec then talks about the time when he worked at the Bank and how he was in charge of paying the agents.
To gain Peter’s trust, Alec tells him how he built his community of spies in Berlin and how he would take his car almost every week to the woods and let it there with a basket filled with money. Then, when he would return, he would find tins with film with documents and pictures incriminating for the Communist party. In time, Alec figured out that the man who must have given him the information is Riemeck, a member of the East German Government. Peters asks if he never thought about the possibility of Riemeck being helped but Alec admits that he never asked that question. Peters makes Alec question Riemeck by suggesting that there was no way he could have found all those information by himself. Peters also tells Alec that Elvira was killed just a week before.
After this conversation, Alec thinks that maybe the person Control told him to find and protect was the one who gave away all that information. He then reasons that maybe Elvira was killed because she knew too much and then he worries about Liz back home, thinking about her safety.
The next day, Alec tells Peters that he learned the names of a few spies while he was working for the bank. He gives Peters the list with the names and tells him about a mission he had named ‘’Rolling Stone’’, a complicated operation that had the purpose of making sure that a large sum of money ends in the hands of one of their spies. Alec was not given almost any information about the mission and Peters implies through this that Control does not trust him.
On the third day, Peters fails to show up early in the morning. When Peters arrives in the evening, he shows Alec a newspaper from England, showing that he became a wanted man. After hearing this, Alec realizes that Control wants him to go even deeper and that his assignment may be prolonged as a result. Peters also tells Alec they have to go to Berlin where he will be interrogated further. Not having another choice, Alec agrees to go. At the airport, Alec buys a British newspaper and finds that Peters was right about he being a wanted man.
In the eleventh chapter, the narrator presents Liz who remained in London. She went to his apartment once after he left and found that surprisingly, his rent was paid by two men. She also thinks about the strange behavior he had the night before he hit the store clerk and she suspects that everything was planned. Liz is also visited by two men and she tells them what she knows about Alec. Liz is told that Alec had a family and children and Liz was surprised to hear this. One of the men gives Liz a card, saying to call if she needs any help or if she is contacted by Alec. When they leave, Liz looks at the card and sees the name George Smiley printed on it.
In the 12th chapter, the narrator returns to Alec who is on a plane to Berlin. On the ride there, Alec convinces himself that he must continue to trust Control no matter what and follow his instructions.
In Berlin, Alec is taken to the communist side and then at the GDR headquarters to be further interrogated. Alec suspects that he will be interrogated by a Jew named Fiedler, known for his sadistic methods and for his ruthlessness. Peters and Alec arrive at a hunting lodge where they are meet by Fiedler who tells Alec that he will not go further East and that he will remain in Berlin. Alec acts surprised and starts shouting how he was fooled into betraying his country by making him believe he will be accepted by the Communists. Fiedler claims that they were not the ones who told the Circle about his betrayal and then revealed that he planned to use Alec to promote himself in Mundt’s eyes. Fiedler also claims that it was necessary for Alec to come to Berlin because he did not told them everything he knows and they plan to make him tell them things even he was not aware he knew.
The next day, Fiedler comes again, asking Alec about the operation Rolling Stones and about the files Alec was given. Alec tells Fiedler about the files and how they were passed from one person to another but claims not to know what happened to them because he was drinking then. At the end of the conversation, Alec shouts at Fiedler that there was no way some other person could work in Germany for the Circle without his knowledge especially when considering the position he had.
Fiedler is also interested to find about the way the Circus justifies the actions they do and how many from the Circus have no problems killing people even though they are Christians, a religion claiming that every life is precious. The two then talk again about Rolling Stone and Alec tells Fiedler that he thinks the money were supposed to reach someone working behind the Iron Curtain. Fiedler then proposes they call the bank where Alec put the money to find weather the money was withdrawn by the mystery man or not. Alec agrees to write to the bank but only after Fiedler persuades him into believing he needs a friend.
When Alec remains alone, he starts thinking how maybe Fiedler was the one he was supposed to protect and how Fiedler was his only chance of getting home again.
The next day, Alec writes the letters and is told he must remain for one more week with Fiedler until the banks respond back. That same day, the two talk about Mundt and how the British authorities failed to catch him after he killed a man in England. Alec tells Fiedler that Mundt was left to leave on purpose and Fiedler makes Alec question the reason why Mundt was not arrested.
In another day, Alec and Fiedler go on a ride and Fiedler begins talking with Alec about Mundt. In Fiedler’s opinion, Mundt’s tactic of killing everyone is not practical because in that way, they lose valuable information. Because of this, Fiedler suspected that Mundt was the man who was a British spy and that was the reason why he was left to live. What is more, Fiedler shows Alec a letter from the bank, being told that the money was withdrawn from the account. The same day when the money was withdrawn coincided with the day when Mundt left for the city where the bank was located.
The narrator moves back to Liz who received a letter telling her she will need to go for a few days to Leipzig as an exchange secretary for the communist party. Even though she finds the letter strange, she agrees to go on the trip, thinking that she will never be able to afford it on her own and that it will help her forget about Alec.
In chapter 14, Alec returns to the house. He becomes suspicious because of what he was told and he becomes violent towards one of the guards, beating him with a chair. He is knocked out by other guards and when he wakes up, he is in a strange room, tied up. Soon after waking up, a man enters the room. Alec recognizes the man as being Mundt.
Alec is then untied and taken to another room where he is told that Fiedler is being detained under house arrest for consipiring against the Party. Alec is told the guard he attacked died and that he must confess against Fiedler if he wants to be treated kindly in court. Mundt also tells Alec that he knows he was sent by the Circus in an attempt to frame him. Mundt continues to ask Alec questions but he soon becomes unable to answer them as he is hurt. Alec soon passes out once more and when he wakes up he is in a hospital with Fiedler.
Fiedler tells Alec that Mundt was arrested because of his anti-Semitic behavior and that he will be taken to court soon enough and that he will most likely be sentenced to death. Alec falls asleep again but not before being told by Fiedler that their governments and their way of operating are not that different.
In chapter 19, the narrator returns to Liz who is in Leipzig attending a Communist meeting. At the end, she meets with a man named Holten who claims to want to take Liz to a special meeting. Liz enters a car but she feels as if something is wrong.
In chapter 20, Mundt is at the Tribunal where he is judged for his crimes. Fiedler and Alec are present and Fiedler presents the case against Mundt. Fiedler claims that Mundt played for both sides and feed intelligence both to the British and to the Germans. In Fiedler’s opinion, the reason why he did that was because he wanted more money. Alec is asked a series of questions by the judge but he continues to claim that Mundt could not have been working for the British because he had no knowledge about it. Alec also talks about Karl and the information he had access to and theorizes that that information may have been given to him by Mundt. Alec also claims that Mundt killed Karl because he knew too much and became a liability.
In the next chapter, Mundt’s lawyer, Karden, tries to make the jury believe that Mundt is innocent. He claims the British try to frame Mundt to cover their own tracks and that Fiedler was fooled into believing Mundt is a traitor. The lawyer claimed that Mundt knew about the plot and had someone follow Alec’s every move to try and find if he was living a double life. Karden claimed that Alec made a mistake during his mission and Alec is called one more time to testify. Alec is called a serious of question about his financial status, friendship with Smiley and former jobs before the lawyer asks another witness to be bough forth. The witness is Liz who is surprised to see Alec when she enters the room.
Alec screams about leaving Liz alone. Liz meanwhile does not know who is on trial and she is asked a series of questions about Alec and their relationship. The court also tells Liz that she must think about the Party and its interests above all while answering the questions. Under pressure, Liz tells the court how two men came and paid Alec’s rent after he left and how she began getting money as well periodically for someone she did not knew. She also talks about the store clerk Alec hit before he was sent to prison and how she heard the man talk about how he was paid after the trial. She also talks about Smiley and how he went to Liz after Alec disappeared. After Liz is done being questioned, the lawyer tells the judge that it is clear that Mundt was framed.
After the testimony is done, Alec realizes that someone must have feed inside information since some detail presented in the court were supposed to be known only by the members of the Circle involved in the operation.
Liz is taken out and Fiedler goes with her, to question her. Alone, Alec admits to everything and tries to save Fiedler and Liz. The court’s decision is to fire Fiedler and to send Alec to another court to be judged there. In that moment, Alec also realizes that he was actually sent to frame Fiedler.
In another prison, Liz is told that she will be incarcerated as well. She also finds that Fiedler and Alec will be executed for their crimes.
That night, Liz is awaken in her cell by Mundt who takes her out of the prison and takes her Alec who is waiting outside with a car. In the car, Alec tells Liz the truth about the operation. Mundt was indeed a British spy and Fiedler began suspecting him. Because of this, Alec had to do what it takes to make the state kill Fiedler to protect Mundt. Alec tells Liz that he did not knew all the details to the mission and that he believed until the very last moment that Mundt was the one who had to die. He also tells Liz that the Circus used her to get to Alec and to manipulate the Communist party.
On the road, Alec picks up a man who tells them where they can cross safely over the Wall and he disappears as soon as the car reaches the spot. Alec is told he must climb first and then take Liz with him. the two wait just for the right time before they make a run for the Wall. Alec manages to climb the Wall safely but before Liz can cross as well, she is shot and killed. Alec, not wanting to be used once more by his government, decides not to cross.
The book ends with Alec holding Liz in his arms and then being fatally shot as well.
