"The Tunnel" is a novel by Ernesto Sabato, an Argentine author. It tells the story of Juan Pablo Castel, a painter who becomes obsessed with a woman named María. The narrative explores themes of isolation, existentialism, and the darker aspects of human nature. The book is written in the first person, allowing readers to delve into Castel's troubled mind. As he recounts his life and his fixation on María, the story unfolds with tension and psychological depth, ultimately leading to tragic consequences. "The Tunnel" is considered a significant work in Latin American literature.