Ten-year-old Harry Potter has, thus far, led a miserable life. He lives with his Aunt Petunia and Uncle Vernon, because his parents died when he was very young. While they spoil their own son, Dudley, they frequently punish Harry, especially when odd things happen around him that he is unable to explain. One day, hordes of letters begin to arrive in the mail for Harry, but Vernon intercepts them.
On Harry’s eleventh birthday on July 31, an enormous wizard named Hagrid appears and explains to Harry that he is a wizard, too. Harry’s parents, Lily and James, were wizards who sacrificed themselves to save him from a supremely evil wizard named Voldemort. When Voldemort tried to kill baby Harry, however, he was inexplicably unable to—he only left a lightning bolt-shaped scar on Harry’s forehead. Thus, Harry is famous all over the wizarding world as “the boy who lived.” Hagrid then delivers one of the letters, which invites Harry to Hogwarts, a school for witchcraft and wizardry.
The next day, Hagrid takes Harry to Gringotts, the wizarding bank, where Harry’s parents have left him a small fortune. Hagrid also shiftily retrieves a small package from a different vault, though he won’t tell Harry what it is because it is secret business for Hogwarts. Harry then buys his school supplies (robes, cauldrons, spellbooks, and a wand) but starts to worry that he doesn’t know anything about magic. Hagrid assures him that he’ll learn quickly.
A month later, Harry takes the train to Hogwarts. He quickly befriends a boy named Ron Weasley, who is also a first year, on the train. Harry also meets a boy named Draco Malfoy, whom Harry immediately dislikes for his arrogance and cruelty. They also meet Hermione Granger, a precocious girl whom they peg as a know-it-all. When they arrive at the Hogwarts Castle, the students are immediately sorted into four Houses based on personality by a “sorting hat.” Harry is relieved not to be sorted into Slytherin, which was Voldemort’s House and is known to prize ambition (and into which Draco is sorted). Instead, he is sorted into Gryffindor, a House that is known best for bravery, along with Ron and Hermione.
Harry begins his classes, learning subjects like transfiguration, charms, herbology, defense against the dark arts and astronomy. When he has his first Potions lesson, however, the teacher, Professor Snape, takes an instant dislike to him, though Harry is not sure why.
Harry and the Gryffindors go on their first flying lesson the next week, along with the Slytherins, and though he flies when he is not supposed to, Professor McGonagall (Head of Gryffindor House) sees his innate talent and recruits him for the Gryffindor Quidditch team (a wizarding sport played on brooms).
That night, Malfoy challenges Harry to a wizard’s duel at midnight in the trophy room, and Harry and Ron sneak out that evening despite Hermione’s protests. They are almost caught, and they duck into a forbidden third-floor corridor in order to avoid being found. They realize, however, why the corridor is off-limits: it has a giant three-headed dog inside, which is guarding a trapdoor.
On Halloween, Ron comments on how annoying Hermione is and how she has no friends, which Hermione overhears. She spends the day crying in the girl’s bathroom. That night, the Halloween festivities are interrupted when the defense against the dark arts teacher, Professor Quirrell, announces in a panic that there’s a troll in the dungeon. Instead of going back to their dorms, Harry and Ron seek out Hermione to warn her about the troll (also noting on their way that Snape is suspiciously heading in a different direction from the other teachers). Harry and Ron then encounter the troll in the bathroom where Hermione has been taking refuge all day, and Ron is able to knock it out. When the teachers discover what they have done, Hermione lies to keep them out of trouble, and Harry, Ron, and Hermione become friends. Harry later discovers that Snape had in fact tried to get past the three-headed dog during this event, and concludes that he must be trying to steal whatever the dog is guarding.
In November, Harry plays his first Quidditch match. The game starts well for Gryffindor, until Harry’s broom starts to try to buck him off. Hermione realizes that Snape, who is sitting in the stands with the other spectators, is jinxing Harry’s broom. She sets Snape’s cloak on fire, breaking his concentration, and Harry is able to win the match for Gryffindor.
Hagrid accidentally admits to the three friends that the dog is guarding something that has to do with a man named Nicolas Flamel. The kids pick up on this clue, and try to look up Flamel in the library. However, they don’t know where to look, and as the holidays approach, they are still unsuccessful in finding out who he might be.
Hermione goes home for the holidays, but Harry and Ron remain (Ron’s parents are visiting his brother Charlie in Romania). Harry and Ron spend their days playing wizard’s chess (the same as Muggle chess, except the pieces are alive). On Christmas, Harry receives presents for the first time, including a handmade flute from Hagrid. One present is an Invisibility Cloak, a rare and valuable object that makes the wearer invisible. Harry doesn’t know who it’s from: the note that came with it merely says the cloak had belonged to James, and that the person who ended up with the cloak after James’ death wanted to return it to Harry. That night, Harry sneaks into the Restricted Section of the library to see if he can find a book with information on Flamel. But as soon as he picks up a book, it starts screaming, and so he runs down the corridor and into an unused classroom, hoping to avoid the school’s nasty caretaker, Filch.
While hiding in the classroom, Harry notices a large mirror—the Mirror of Erised. When Harry looks into it, it shows Lily and James behind him. He grows consumed by what he sees, returning to the Mirror the next night with Ron, and a third night alone despite Ron’s warnings that Harry is obsessing over it. On the third night, the Hogwarts headmaster, Dumbledore, confronts Harry about the mirror, and explains that it shows the deepest desires of a person’s heart. He tells Harry that the mirror will be moved the next day, and warns him not to go looking for it, as people have wasted their lives sitting in front of it, driven insane by what they see in the reflection.
With a fortuitous clue from a collectible wizard card, Harry, Ron, and Hermione discover that Flamel is the only known maker of the Sorcerer’s Stone, which can turn metal into gold and produces the Elixir of Life, which makes the drinker immortal. Meanwhile, Harry grows increasingly suspicious of Snape, who he believes wants to steal the Stone, and also tries to get more info from Hagrid about Fluffy. When Harry visits Hagrid, Hagrid is illegally hatching a dragon that he won from a stranger in a card game. Harry worries that Hagrid will get in trouble for keeping this dragon, and so he and Hermione use the Invisibility Cloak to sneak out of bed and drop Norbert off with friends of Ron’s brother Charlie, who works with dragons. After successfully bringing Norbert to safety, Harry and Hermione are caught trying to return to Gryffindor. They lose 150 points for Gryffindor for being out of bed after hours, and receive detention.
Their detention is served in the Forbidden Forest, where they are looking for something that has killed a unicorn. In the Forest, Harry sees a cloaked figure drinking the blood of a unicorn. The figure menacingly starts to come after Harry, but a centaur named Firenze steps in, saving Harry from the figure. Once Harry is safe, Firenze explains that the figure was Voldemort, and that he was drinking the blood of the unicorn because unicorn blood will keep a person on the brink of death alive.
With this knowledge, Harry then starts to worry that Snape is going to steal the Stone for Voldemort in order to give him immortality. A thought strikes him: it’s odd that someone happened along with an illegal dragon egg, which Hagrid desperately wanted. Harry questions Hagrid, who reveals that he informed the hooded stranger with the dragon that the key to taking care of any creature is knowing how to calm it down. With Fluffy, for example, all one has to do is play music, which puts him to sleep.
Hearing this, Harry is convinced that the stranger was either Snape or Voldemort. And after Dumbledore is called away on urgent business, Harry is certain that Snape will try to steal the Stone that night and aims to get it first. Ron and Hermione prepare to go with him, while a nervous boy named Neville tries unsuccessfully to prevent them from leaving the dormitory and getting in more trouble. Harry, Ron, and Hermione then work together to overcome the spells and enchantments guarding the Stone.
Harry ultimately makes it to the final room alone. There, Harry discovers Quirrell is actually the one who had been doing Voldemort’s bidding, not Snape. Voldemort has been hiding underneath Quirrell’s turban, only a face on the back of the man’s head. Harry is able to acquire the Stone by looking into the Mirror of Erised. His reflection places the Stone in Harry’s pocket. Quirrell tries to take the stone, but is inexplicably burned when he touches Harry. Harry tries to hold on to Quirrell in order to prevent him from getting the Stone, but the pain mounts in his scar, and he faints.
Harry wakes in the hospital, where Dumbledore explains why Quirrell was unable to touch him: the love that Lily showed in sacrificing herself for Harry gave him a magical protection from Quirrell and Voldemort. Dumbledore also reveals that he intends to destroy the Stone to prevent anyone from using it for evil.
At the end of the year feast, Dumbledore awards Ron, Hermione, Harry, and Neville 160 points collectively for their bravery, earning Gryffindor the House Cup. At the end of the year, Harry returns to the Dursley’s home, but is happy knowing that he now has friends and people who love him—and that the Dursleys don’t know he’s not allowed to do magic at home.