During his third year at Hogwarts School of Witchcraft and Wizardry, a young wizard is warned of danger when a notorious prisoner escapes from the supposedly impregnable wizarding prison, Azkaban. The prisoner, rumored to be a loyal supporter of the dark wizard who murdered the boy's parents, is believed to be seeking him for vengeance. As tension builds, the school is guarded by Azkaban's soul-sucking guards, the Dementors. However, the boy finds moments of light amidst the darkness, reuniting with his best friends who stand steadfast by his side. Together, they delve into advanced magical classes, where they learn to confront fearsome magical creatures and master spells to repel the Dementors' chilling influence.

The boy also encounters new faculty members, including the enigmatic new Defense Against the Dark Arts teacher, who has a profound influence on the boy, teaching him how to harness his inner strength. Meanwhile, the boy struggles with the nuances of adolescence, experiencing the complexities of friendship, loyalty, and identity as past truths come back to light. With danger closing in, he must decipher a maze of secrets and confront the reality of his own haunting destiny. Through it all, discoveries within the enchanted walls of Hogwarts place the boy and his friends in the very heart of the unfolding mystery, drawing them closer to the true nature of the escaped prisoner and the histories intertwined with his own.