Professors Albus Dumbledore, Minerva McGonagall, and gamekeeper Rubeus Hagrid from Hogwarts School of Witchcraft and Wizardry deliver the orphan, Harry Potter, to his only living relatives, the Dursleys. Harry grows up, unaware that he is a wizard and is led to believe his parents were killed in a car crash.

Ten years later, owls begin delivering letters addressed to Harry. To prevent them, the Dursleys drag Harry to a deserted cabin where Hagrid arrives, confirming that Harry is a wizard and has been accepted to Hogwarts, having been lied to by the Dursleys. Hagrid brings Harry to Diagon Alley to purchase his school supplies, and buys him a snowy owl, which Harry names Hedwig. The core of Harry’s chosen wand has a feather from Dumbledore’s phoenix, just like the wand of Lord Voldemort, the dark wizard. Hagrid tells Harry that Voldemort murdered his parents. However, when he tried to kill Harry, his curse rebounded, leaving Harry with only a scar. Voldemort was defeated, for which Harry became famous.

On the Hogwarts Express, Harry befriends Ron Weasley, a pure-blood wizard from a poor family, and Hermione Granger, a Muggle-born. He rivals Draco Malfoy, who is hostile toward Ron due to his status. The first-year students are sorted into four houses: Gryffindor, Hufflepuff, Ravenclaw, and Slytherin, known for producing dark wizards. Harry, Ron, and Hermione join Gryffindor, while Malfoy goes to Slytherin.

Harry becomes the seeker for Gryffindor after McGonagall sees his flying skills while retrieving Neville’s Remembrall from Malfoy. Harry, Ron, and Hermione find the forbidden corridor guarded by a three-headed dog, Fluffy. After Ron insults Hermione on Halloween, she retreats to the girls’ bathroom. At the feast, Professor Quirrell announces that a mountain troll has entered the school. Harry and Ron save Hermione, and she lies to McGonagall, claiming she was looking for the troll and they rescued her, saving Ron and Harry from punishment.

Harry suspects that Professor Severus Snape, head of Slytherin, let a troll steal what Fluffy guards after he sees Snape limping. During Harry’s first Quidditch match, his broom acts wildly; Hermione and Ron suspect Snape is jinxing it as he stares at Harry, mouthing a curse. To distract him, Hermione secretly sets his robes on fire. Hagrid doubts their claims. When the trio expresses that Snape intended to bypass Fluffy, Hagrid unintentionally reveals that Fluffy guards something known only to Dumbledore and Nicholas Flamel.

Harry and Ron spend Christmas together, where Harry receives the Cloak of Invisibility and discovers the Mirror of Erised, which shows one’s deepest desire. Dumbledore warns him about its dangers. When Hermione returns, they learn that Nicholas Flamel created the philosopher’s stone, granting immortality and guarded by Fluffy while Snape seeks it. Hagrid receives a dragon egg and sends Norbert to Romania. In detention, Harry is attacked by a hooded creature feeding on unicorns but is saved by a centaur named Firenze, who reveals the creature is Voldemort, seeking immortality through the stone.

As the trio suspect Snape of stealing the stone for Voldemort, they learn from Hagrid that music helps them pass Fluffy. That night, realizing Dumbledore has gone to London, they descend the trapdoor to confront Snape. After getting past Fluffy, they face three challenges: devil’s snare, flying keys, and an enchanted chessboard. Ron gets injured in the third challenge, so Hermione tends to him while Harry confronts their suspect, who is actually Quirrell. Quirrell reveals that he tried to kill Harry and that Snape was protecting him. He shows Voldemort’s weakened form on the back of his head, trying to force Harry to give him the stone. Harry refuses, prompting Voldemort to order Quirrell to kill him. Harry’s touch incinerates Quirrell, leading to his death and Voldemort’s spirit escaping.

In the hospital wing, Dumbledore informs Harry that the stone is destroyed and explains why he defeated Quirrell easily; his mother’s sacrifice left a protective mark. At the end-of-term feast, Harry, Ron, Hermione, and Neville earn house points, enabling Gryffindor to win the cup despite Slytherin’s early lead. As summer nears, Harry is happy to have found a real home at Hogwarts.