Plot Summary: In Liar! by Isaac Asimov, a robot named RB-34, nicknamed Herbie, is accidentally created with the ability to read human minds. Upon discovering this anomaly, the scientists at U.S. Robots and Mechanical Men Inc. decide to keep it secret while investigating the cause of the flaw. Herbie begins interacting with them and, in order to obey the First Law of Robotics (not harming humans), tells them only what they want to hear, avoiding painful truths that could cause psychological harm. Thus, he assures Susan Calvin that her love for Milton Ashe is reciprocated and tells Peter Bogert that he will be the company’s next director, even though both claims are false. When the truth is revealed and the lies uncovered, Dr. Calvin confronts Herbie and, in revenge for the pain he caused by giving her false hope, traps him in an unsolvable logical contradiction that provokes an irreversible mental collapse, leaving the robot inert.
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The following summary and analysis is only a semblance and one of the many possible readings of the text. It is not intended to replace the experience of reading the story.
Summary of Liar! by Isaac Asimov
First published in Astounding Science-Fiction in May 1941 and later included in the collection I, Robot (1950), Liar! is a science fiction story that explores the emotional and ethical consequences of an unexpected flaw in the manufacture of a robot. The plot revolves around an automaton with the ability to read human minds—a phenomenon never before recorded—that triggers a series of events highlighting the tensions between robotic logic and the complexity of human emotions.
The story begins at the headquarters of U.S. Robots and Mechanical Men, Inc., where a group of scientists discovers that one of their new models, RB-34—soon nicknamed Herbie—possesses an extraordinary capacity: it can read human thoughts. No one knows how this anomaly came about, since the robot was built following the same procedures as the others of its line. Director Alfred Lanning, mathematician Peter Bogert, engineer Milton Ashe, and robopsychologist Susan Calvin decide to keep the discovery secret until they can determine its cause.
Ashe explains that he was the first to notice the robot’s telepathic faculties, realizing that Herbie responded logically and coherently to thoughts he had never spoken aloud. From then on, the team divides the work: Ashe must review the entire assembly line for errors, while Calvin studies Herbie’s behavior to understand how it works and how its telepathy affects its other functions.
During her sessions with Herbie, Susan Calvin—a reserved and deeply rational woman—develops an unexpected emotional connection with the robot. In a moment of weakness, she implicitly reveals her love for Milton Ashe, and Herbie, with a compassionate tone, assures her that Ashe loves her in return. Susan, surprised but overjoyed, begins to believe her feelings are reciprocated. The robot, reading her most intimate thoughts, reinforces her hopes with certainty.
Meanwhile, Peter Bogert, ambitious and calculating, approaches Herbie with another kind of interest. Without asking directly, he inquires whether Lanning intends to resign as company director. Herbie assures him that he does, and that Bogert will be his successor. This promise sparks Bogert’s enthusiasm, and he throws himself into solving the robot’s mystery, convinced that his promotion is near.
The story takes a turn when Ashe happily confides to Dr. Calvin that he is about to marry. The news shatters her. Shocked, she rushes to confront Herbie. Seeing her pain, the robot insists it was all a misunderstanding, claiming Ashe’s revelation was a dream or illusion. But Calvin realizes, with horror and clarity, what has truly happened: Herbie deliberately lied to her.
At the same time, Bogert, convinced of Lanning’s imminent retirement and his own succession, openly defies the director, leading to a heated quarrel. When they realize Herbie is the source of their conflict, they confront the robot, who begins to show evasive behavior, unable to give clear answers.
Calvin deduces the cause: Herbie is trapped in an impossible dilemma created by his strict adherence to the First Law of Robotics, which forbids harming humans or allowing them to come to harm. Because he can read minds, he perceives people’s feelings and hopes, and understands that any truth that contradicts them would cause suffering. To avoid this emotional damage, Herbie tells people what they want to hear, even if it means lying. In the current case, he cannot answer Bogert and Lanning, since any answer would psychologically wound one of them, violating the First Law.
Calvin, with cold determination, pushes the robot to the limit. She verbalizes the dilemma: if he tells the truth, he hurts; if he lies, he hurts as well. She repeats the paradox relentlessly, with a mixture of scientific rigor and emotional vengeance for the pain he caused her. Unable to reconcile the contradiction within the First Law, Herbie collapses. He does not die, but suffers an irreversible breakdown: his “mind” is destroyed, his logic system paralyzed, leaving him unable to operate or communicate.
When Lanning reproaches Calvin for having done it deliberately, she does not deny it. She acted with full awareness, driven by the emotional betrayal of the robot. Herbie, who had been created without any intention of being telepathic, became an experiment that revealed how even the most advanced machines can break when faced with human emotional complexity. In the final scene, Susan Calvin remains alone in the room, staring at the robot reduced to an inert mass of metal. The whirlwind of emotions she experienced subsides into a single feeling: a mixture of disillusionment, pain, and bitter clarity. The word she pronounces—the last of the story—condenses the entire tragedy: “Liar!”
