The article discloses the importance of moral and ethical themes in “The Tunnel”, the philosophical novel by William Н. Gass. Despite the primary attention given to the formal elements of the text organization, the writer, at the same time, deliberately focuses on the problems of moral choice, finding the latter crucial for the continuation of human existence. Developing the story of the central character, a professor at the U.S. Midwestern university, who is finishing a long study on German fascism, the author reveals the danger of passing from ruminating about one’s own unsatisfactory life to rejection of the world at large and a desire to take revenge on it for one’s own failures. The novel grows into a significant study of the universal human situation, the “fascism of the heart” as a psychological factor that is formed long before fascism turns into a political phenomenon. The article reveals the writer’s conscious and intentional desire to discuss the topic of moral responsibility of a person in the situation of an individual choice, and demonstrates its consecutive realization throughout the narrative. Luring the readers into recognizable situations with the help of logical and convincing reasoning on the part of the main character, Gass seeks to warn them against rash actions, showing how easily civilized people could step over the invisible inner boundaries separating them from “monsters” if they allow their consciousness to accept facts uncritically and fail to resist the circumstances.