After a dementor attack in his Muggle neighborhood, Harry returns to the world of wizardry only to find that the magical community is in denial about Lord Voldemort's return. The Ministry of Magic is interfering at Hogwarts, appointing the rigid and ruthless Dolores Umbridge as the new Defense Against the Dark Arts teacher. She quickly imposes oppressive rules and refuses to teach practical defensive magic. Harry, Hermione, and Ron realize the need to take matters into their own hands, leading to the creation of a clandestine group dedicated to learning defense against the dark arts. Named "Dumbledore's Army," this group grows in numbers, gaining strength and unity under Harry's guidance.

Meanwhile, the overarching power of the Ministry shows its force as Cornelius Fudge instills fear among the magical society about Dumbledore's influence and intentions. Prophetic dreams continue to disturb Harry, suggesting a deeper connection to the Dark Lord. With the truth of Voldemort's return at stake and skepticism surrounding his own experiences, Harry is pushed toward an ominous path—one that leads to mystery, danger, and the uncovering of long-held secrets within the wizarding world.