Set in ancient India during the time of Gautama Buddha, the novel follows the spiritual journey of a wealthy Brahmin's son named Siddhartha. Dissatisfied with traditional religious rituals, he leaves his home to search for the ultimate truth and meaning of existence. His path takes him through strict asceticism, extreme worldly wealth, sensual desires, and deep despair, before he finally finds true wisdom and peace by listening to the quiet soul of a river.