The Forbidden Forest

Professor McGonagall catches Harry, Hermione, and Neville out of bed, assumes they lured Draco with a dragon story, and assigns all three detentions while deducting fifty points each, sinking Gryffindor to last. Gryffindor turns on them, and even Quidditch loses its joy. Harry overhears Professor Quirrell being coerced and suspects Professor Snape has forced him to yield.

Detention notes summon Harry, Hermione, and Neville to meet Filch at night, along with Draco. Hagrid takes them into the Forbidden Forest to track a wounded unicorn, splitting them into two groups and instructing them to signal with sparks if they find trouble. With Hagrid and Hermione, Harry meets centaurs Ronan and Bane, who speak in riddles about the stars and offer no direct help.

Red sparks from Neville and Draco draw Hagrid away; Draco had frightened Neville as a prank. Hagrid reorganizes the parties, sending Harry with Draco and Fang. They follow thickening blood to a clearing and find a dead unicorn. A hooded figure crawls out, drinks the unicorn’s blood, and advances on Harry. Harry’s scar sears with pain as Draco and Fang flee.

A young centaur, Firenze, charges the figure away and rescues Harry. Ronan and Bane confront Firenze for carrying a human and for “interfering” with fate, but Firenze insists the danger justifies it. While carrying Harry out, Firenze explains that drinking unicorn blood sustains a dying person at a terrible cost, and hints that someone might use it only to survive until they can gain immortality from the Sorcerer’s Stone.

Hagrid and Hermione find Harry; Firenze departs, hoping the planets are wrong. Back in the common room, Harry concludes that Snape aims to get the Stone for Voldemort, who is lurking in the forest. As dawn breaks, Harry discovers his Invisibility Cloak returned to his bed with a note reading, “Just in case.”