The "Father Brown" book series by G.K. Chesterton began with which of the following books?

Father Brown, fictional character, a priest who is the protagonist of a series of detective stories by G.K. Chesterton. Father Brown, one of the most quirkily genial and lovable characters to emerge from English detective fiction, first made his appearance in "The Innocence of Father Brown" in 1911.

G. K. Chesterton's 1911 book was published as a collection of twelve short stories featuring Father Brown, a priest turned detective who combines philosophical and spiritual reasoning with scientific observation to solve crimes. Literary critics said that Chesterton's efforts and actual actions laid the foundation for future detective figures in literature, such as Hercule Poirot, Miss Marple, Ellery Queen, and Nero Wolfe.

Unlike other writers of his time, who concocted outlandish crimes and intricate puzzles for the protagonist to solve, Chesterton (May 1874, London, England— June 1936, Beaconsfield, Buckinghamshire) is said to have pioneered the cozy mystery, narrowing the scope of the investigation to limited time, limited space, and a limited number of suspects, with all of the clues revealed to the reader as well as to the detective. These items found in "The Innocence of Father Brown" are said to have caused practical interest in the book.

Chesterton is seen as a biting social commentator, and the tales in this collection are seen as short, easy reads with strong plots, all connected by the clever detective with an above-average understanding of human nature.