Harry Potter and the Half-Blood Prince

About the film

Contains story spoilers.

The sixth year begins with Voldemort’s return no longer contained within the wizarding world. Death Eaters attack London, including a destructive assault on the Millennium Bridge, and the film shows fear spilling into ordinary public life. At Hogwarts, Dumbledore brings Harry into the effort to understand Voldemort not through another duel but by examining memories. He wants Harry to help persuade former professor Horace Slughorn to provide a memory he has hidden. Meanwhile, Draco Malfoy receives a dangerous assignment from Voldemort. Narcissa visits Snape, who makes an Unbreakable Vow to protect Draco and finish the task if he cannot. The contrast between the opening attack and classroom life makes Hogwarts feel temporarily protected rather than genuinely separate from the war.

Harry’s access to Slughorn’s potions lessons comes through an old textbook filled with handwritten corrections and spells. The anonymous owner calls himself the Half-Blood Prince, and the notes help Harry excel in class. Their usefulness creates a tension between cleverness and trust: Harry gains an advantage from instructions whose author and consequences he does not understand. The dangerous Sectumsempra spell becomes a turning point when Harry uses it on Draco during a confrontation and sees how violently an unexplained line in the book can work. Snape treats the incident as serious, while Harry hides the book rather than surrendering his edge. Harry’s borrowed book improves his results so quickly that he initially treats its author’s authority as trustworthy without asking why it was written.

Social life at Hogwarts keeps moving alongside the threats. Ron joins the Gryffindor Quidditch team, and his confidence rises after Harry pretends to add Felix Felicis to his juice, making him think luck is on his side. Hermione’s frustration grows as Ron becomes involved with Lavender Brown. Harry, meanwhile, realizes that his feelings for Ginny have changed. These threads are not detached comic relief; they show the characters trying to live through an ordinary school year even as old friendships are strained and the adults prepare for a conflict that students can no longer ignore. The film lets flirtation and school competition share space with clues, so the ordinary calendar keeps moving even when the threat is escalating.

Draco’s assignment becomes harder to conceal when a cursed necklace nearly kills Katie Bell and poisoned mead reaches Ron. Harry suspects Draco and watches him closely, but he does not understand the full plan. Dumbledore continues to show Harry memories from Voldemort’s childhood and adolescence, tracing Tom Riddle’s fascination with control and immortality. Harry needs Slughorn’s unaltered memory because it concerns Horcruxes, objects that can conceal pieces of a soul. Harry uses his real dose of Felix Felicis to visit Hagrid during Aragog's burial, where Slughorn is present. Appealing to Slughorn's affection for Lily, Harry finally obtains the unaltered memory. Dumbledore and Harry now have a clearer theory about how Voldemort has tried to make himself difficult to kill. The necklace and mead incidents point toward a pattern of attempted attacks, but they do not immediately reveal how Draco intends to carry out his task.

That knowledge leads to a cave where Dumbledore believes one Horcrux is hidden. Harry accompanies him through an underground lake and helps retrieve a locket from a basin of potion. Dumbledore drinks the potion and becomes dangerously weakened, but the pair get back to Hogwarts. They find that Death Eaters have entered Hogwarts through a paired Vanishing Cabinet Draco has repaired, and Draco confronts Dumbledore in the Astronomy Tower. Harry remains hidden at Dumbledore’s instruction as Draco disarms the headmaster. Snape arrives and kills Dumbledore, then flees with the Death Eaters. Harry pursues him and tries to use the Prince's spells. Snape blocks them and reveals that he himself is the Half-Blood Prince before escaping. The moment turns the film’s school setting into a battlefield and leaves Harry with grief, anger, and a new reason to distrust the book’s mysterious owner. The journey through the cave is one of the few times Harry sees Dumbledore physically vulnerable, changing their familiar teacher-student dynamic.

After the attackers escape, Harry learns that the locket recovered from the cave is a fake. Inside is a note signed R.A.B. saying that the real Horcrux has been taken. The discovery means the mission has not ended with Dumbledore’s death; instead, the work he began has been handed to Harry. He decides not to return to Hogwarts for another year and sets his course toward finding the remaining Horcruxes. Ron and Hermione insist on joining him, making the search a shared commitment rather than a solitary duty inherited from his headmaster. Slughorn’s memory matters because the film connects Voldemort’s search for immortality to choices made long before the current school year.

The film’s school-year rhythm contrasts familiar routines with a tightening sense of surveillance and loss. Classrooms, corridors, and parties continue, but the camera repeatedly returns to Draco’s isolation and Dumbledore’s physical decline. The mystery of the annotated book parallels the memory investigation: both ask Harry to interpret fragments left by someone else. One offers shortcuts and risk; the other gives history a larger shape. By the end, Harry has inherited not just Dumbledore’s unfinished task but also the burden of separating useful knowledge from manipulation, a question that follows him beyond the school gates.