Liza is the twenty-year-old girl whom the underground man meets in the house he goes to after dinner, and she is the only character in the book who responds to him with a gesture he had not written in advance.
She is Russian, from Riga, the daughter of petty bourgeois, and has been in the house, a fashion shop that serves as a front, for two weeks. She owes money to the landlady and says she will leave when she pays it off. He provokes her, then preaches to her, and when he describes marriage for love she hesitates and says: "You sound... as if you were speaking from a book." In the sermon that follows, he takes from her her health, her home, and finally her name. She weeps face down and shows him, proudly, a letter from a medical student, who treats her with respect.
Four days later, she goes to his house and sees him quarreling with the servant Apollon. He shouts out his shame, and she understands "that I myself was unhappy" and embraces him. He feels the urge to dominate her, puts money into her hand, and Liza leaves the note on the table and goes out. The book falls silent about the rest: "Never again did I meet Liza, nor did I hear anything about her."