The book is a profound exploration of identity and the human condition, revolving around a man who is arrested upon his return to his home country, Switzerland, after spending time in America. Although he insists he is not the man, Stiller, that everyone believes him to be, his protests are ignored. The story unfolds as he writes in his prison cell, reflecting on his past life and relationships, and grappling with the question of who he truly is. It's a thought-provoking narrative that challenges conventional notions of selfhood and personal identity.

The novel follows the adventures of an eccentric, violent, and mentally unstable protagonist who is released from an asylum by his psychiatrist. The pair embark on a chaotic journey across Europe and America, encountering a variety of strange and often dangerous situations. The narrative explores themes of insanity, violence, and the human condition, offering a dark and surreal critique of modern society.