R. K. Narayn for me will always be the author of the novel that resulted in the hit TV series Malgudi Days, and the amazing theme song with 54 episodes are available here: https://www.youtube.com/playlist?list=PL0CaUqi81mPlHrIk2K9cvha2Zby0VH35d
However, The Guide by R. K. Narayan is a 1958 novel that resulted in the 1965 movie of the same name, starring the late Dev Ananad and Waheeda Rahman. The full movie is available on Youtube. The full text of the novel is available here. Review in The Hindu. A 120-minute U.S. version was written by Pearl S. Buck, and directed and produced by Tad Danielewski. Movie review of the English version in the New York Times. The film was screened at the 2007 Cannes Film Festival, 42 years after its release.
The story is about Railway Raju and how he transforms from a tour guide in Malgudi to a holy saint. He falls in love with Rosie, a married dancer, lives with her after she runs away from her husband, Marco, and helps her to become famous. He is imprisoned for two years on a forgery charge and then transforms into a saint based on the advice that he dispenses to the villagers. He takes shelter in a temple and starts talking to one of the villagers, Velan, who unconsciously helps him in this metamorphosis. In a miscommunication, Raju ends up taking a vow to feast for twelve days to bring rain to the village. The ending is inconclusive as to whether he lives or dies.