What was the title of C.S. Lewis’s first published book of fiction?

The Pilgrim’s Regress was C.S. Lewis’s first published book of fiction.

Published in 1933, The Pilgrim’s Regress: An Allegorical Apology for Christianity, Reason and Romanticism follows a character named John through an allegorical landscape. The book reflects Lewis’s intellectual and spiritual development after his return to Christianity.

Its title and structure deliberately recall John Bunyan’s The Pilgrim’s Progress, but Lewis’s work is not a simple continuation or adaptation. It uses philosophical dialogue, symbolism, and references to modern intellectual movements to examine desire, reason, faith, and authority.

Out of the Silent Planet is often mistaken for Lewis’s first fiction because it became his first major science-fiction novel and opened the Space Trilogy. Dymer, published in 1926, was an earlier long poem rather than his first published fictional prose book.