Dorante, a young gallant who has come to Paris to get his social education and not to take a wife (as his father, Geronte, wishes), hires as his mentor Cliton, a valet who has military and amatory connections. The young man wishes to be schooled in the ways of the world, though the only advice he ever takes from Cliton is to spend freely. Quite by planned accident, Clarice, tired of waiting for her lethargic lover, Alcippe, to conclude their secret arrangements to marry, trips onto the waiting arm of the newly arrived student. Although a rustic, Dorante immediately accommodates himself to the situation and exchanges euphemistic compliments with the young coquette, much to his valet’s despair. The brazen liar captivates not only Clarice but also her companions—especially Lucrece, who is silent throughout—with his false accounts of the wars in which he has fought and the deeds he has accomplished in Germany during the last four years.

The arrival of Alcippe puts the young women to flight, but not before Alcippe sees Clarice talking to his old friend Dorante. Dorante then quite ecstatically informs his companions that he has had amazing amatory adventures during his month’s stay in Paris. Last night, for example, he entertained a beautiful lady and five companions on five boats with four choirs of instruments playing all night and with dancing until dawn after a sumptuous repast of six courses, and so on. Cliton attempts to break into this mad monologue, but with no result, for Dorante’s philosophy is to tell big lies about wars and adventures in order to be believed.

Dorante’s stories are so plausible and his manner so persuasive that the two young ladies fall in love with him. His friend Alcippe burns with jealousy because he thinks that his fiancé was on the barge with Dorante the previous night, and his friend Philiste is completely mystified when he tries to reconcile the tales with what he later finds to be the unvarnished and unromantic truth. The one flaw in the liar’s plans is that in his conversation with Cliton, who has gained information about the young women from a coachman, Dorante has confused Clarice with Lucrece.

Into this confused web of mendacity and misplaced affections comes the good-natured Geronte, who, without his son’s knowledge, presses the young man’s suit for marriage with the daughter of an old friend. The young woman is Clarice, ready and willing to be wooed after all the time she has spent waiting for Alcippe’s advances. The old man and Clarice contrive a meeting that evening under her balcony and incognito, though she doubts that she can judge her suitor’s character from such a distance and under such unintimate circumstances. A friend then suggests that she receive him at Lucrece’s house and as Lucrece.

Alcippe, consumed with jealousy, angrily accuses Clarice of infidelity. Although she denies his charges, she refuses to seal their engagement with two kisses, her hand and her faith. Alcippe, thinking himself the injured party, swears revenge.

Meanwhile, the tolerant father retracts his offer of his son’s hand in marriage to Clarice because the young scoundrel has invented a touching story to escape the wedding planned for him. The story, a cloak-and-sword melodrama, concerns his marriage to a poor girl whose father found them alone; in his anxiety to disguise their presence his gun went off, his sword was broken, his barricade smashed, and her reputation threatened—what could he do but marry sweet Orphise? Cliton’s despair changes to admiration now that he realizes how useful his master’s ability at lying can be. Although Cliton tries to explain to Dorante his mistake about the shy, virtuous, and quiet Lucrece, with whom Dorante has not spoken, the bewitched swain swears he will keep his appointment under the balcony. Alcippe writes a letter breaking off his friendship with Dorante and demanding satisfaction. In one short day, his second in the big city, the provincial student has quarreled, made love, and reported a marriage. To lie effectively, Cliton observes, one must have a good memory.

Confronted by his accuser, Dorante tells Alcippe and Philiste that he has known Clarice for several years and is not interested in her. He has, he says, taken a beautiful married woman with him on the barge, a woman whom Alcippe could not possibly know. He cautions Alcippe not to believe all he hears and not to be led by the green-eyed monster. When Philiste reveals to Alcippe that the young dandy arrived only the day before from the college at Poitiers—proof that although he might be valorous, his reported deeds are imaginary—Alcippe asks the innocent scoundrel’s pardon.

By the time she has exchanged places on the balcony with Lucrece, Clarice also knows about the lies Dorante has told. Lucrece thinks his actions a sign of love. Confronted, Dorante denies all accusations save one; he declares that he pretended marriage in order to wed his Lucrece—at this point there is consternation on the balcony—whom he will marry that next day as proof of his sincerity. By group action he is ordered hence, so shocked are the young ladies at his effrontery—or naïveté.

Dorante now promises Cliton that he will not lie anymore, or at least he will give a signal when he does. He then immediately lies by saying that the rumor of his fight with Alcippe is true and that the unfortunate challenger has been left for dead. He lies again when he claims that the secret of Alcippe’s recovery lies in the magic of a Hebrew word. Hebrew, he claims, is one of his ten languages. He lies also to Sabine, the servant, in order to get back in Lucrece’s good graces, and he invents new names so that his father can send his nonexistent daughter-in-law his good wishes; the duped father is pleased to learn a grandchild is even now six months along. His lies are countered by the lies of the clever Sabine, who lies for money and keeps herself in constant employment by delivering letters and arranging assignations.

By now neither Dorante, Lucrece, nor Clarice knows whom they love. Clarice declares herself in favor of Alcippe, whose father finally settles the marriage arrangements. Dorante then observes that Clarice has been only flirtatious and curious, while the real Lucrece—he declares that he fell in love with the name and henceforth changed the face to fit it—is much deeper. Dorante’s father, declaring as he does so that he will never again help his scoundrel of a son, arranges quite docilely for his marriage. Lucrece, who swears she will love the liar when she can believe him, is suddenly converted to belief when she sees that his avowals are true in spirit. Cliton has known as much all along.