Mr. Vernon Dursley experiences an extremely strange morning.
On his way to work, he sees a tabby cat reading a map, but when he looks back, there isn't a map in sight. Then, as he is stuck in the morning traffic, he catches a glimpse of people donned in cloaks. Later that day, as he walks past a bakery, he hears a conversation about the Potters which unsettles him because he thinks the people may be talking about his sister-in-law’s family.
When he leaves the building of Grunnings, his work place, he runs straight into a tiny man wearing a violet cloak who happily exclaims that You-Know-Who” was finally gone and that a “Muggle” like Mr. Dursley should be pleased. As he pulls into the driveway of Number Four, Privet Drive, the first thing he sees is the tabby cat that he spotted that very morning. Meanwhile, the evening news states unusual reports about shooting stars and owls sighted during the day.
That night, Albus Dumbledore appears out of thin air and chuckles at the sight of the tabby cat sitting on the wall. The street lights flicker into darkness as he clicks the deluminator that he took out of his pocket. When he approaches the cat, he sees a woman named Professor McGonagall in its place. The two of them discuss the disappearance of You-Know-Who, who is also known as Voldemort. Dumbledore relays that Voldemort killed Lily and James Potter, but was unable to kill their son, Harry. Because of this, Voldemort weakens and is forced to flee. Dumbledore then says that Harry is going to be brought up by the Dursleys, which makes McGonagall protest since she saw how awful the family was.
Suddenly, a huge motorcycle lands in front of them. The person that sit astride it is taller than the average man and in his arms is a bundle of blankets.
Dumbledore and McGonagall peer at the bundle of blankets and see a baby boy with a cut on his forehead that was shaped like a bolt of lightning.
Dumbledore takes the boy in his arms and gently lays him on the doorstep, tucking a letter inside the blankets. For a minute, they stare at the bundle. Finally, Dumbledore says that they should leave. The man returns to the motorcycle, and with a kick, the engine roars to life. The motorcycle rises to the air and goes off into the night.
Putting back the lights, Dumbledore sees the tabby cat rounding a corner. He takes one last look at the bundle of blanket and murmurs, "Good luck, Harry."
And with a swish of his cloak, he disappears.
Ten years later, Harry Potter wakes up in a cupboard under the stairs to Aunt Petunia's ear-piercing voice. That day was his cousin Dudley's birthday, and the Dursleys, having no other choice, take Harry to the zoo with them. There, the glass encasing a boa constrictor disappears, . Mr. Dursley assumes that this is Harry's fault and punishes him.
Letters addressed to Harry arrive mysteriously. They just seem to be everywhere - coming out of the chimney, the mailbox, and a few even pressed to the window. Even though Mr. Dursley tries to keep them from Harry, the letters keep on coming. Frightened and disbelieving at the same time, Harry and the Dursleys move out of the the house and go to a secluded island, trying to shake off the constant arrival of the mail. But at midnight, they hear loud knocking on the door, which then swings off its hinges. A giant man enters and hands Harry a letter that states he is admitted to Hogwarts School of Witchcraft and Wizardry. The man introduces himself as Hagrid, the person who took him to the Dursleys ten years ago. Harry learns that the Dursleys knew he was a wizard, but tried to keep it from him.
The next day, Hagrid and Harry go to London to buy school supplies. They go to the Leaky Cauldron where people find themselves in awe of Harry. They stop in front of a brick wall which Hagrid taps thrice and opens to an archway that leads to a cobbled street. Later, Harry finds himself in Gringotts, a Wizarding Bank, where he sees goblins. At Ollivander's, Harry buys a wand that happens to share a core with Voldemort's - the man who was set on killing him.
A month later, Harry boards the train to Hogwarts. There, he meets Ronald Weasley who he immediately befriends. He also runs into Draco Malfoy, an arrogant blond who sneers at him for hanging out with Ron. Hermione Granger also introduces herself to them.
When they arrive at Hogwarts, the Sorting Ceremony takes place. Harry, Hermione, and Ron are sorted into Gryffindor. On the first day, Severus Snape snidely says that Harry is a little celebrity and ridicules him in class. During their first flying lesson, Neville Longbottom injures himself and is taken to the hospital by Madam Hooch. Draco snatches Neville's remembrall—a glass sphere that has smoke that turns red when its owner has forgotten something—and throws the ball in the air. Harry rides on his broomstick and catches it. Professor McGonagall, who saw Harry, says that he should play Quidditch, a game played on broomsticks, for Gryffindor. Later that day, Malfoy challenges Harry to a wizard’s duel at midnight at the trophy room. Harry and Ron go to the trophy room, followed by Hermione, but Malfoy doesn’t show up. While trying to hide, they accidentally discover a three-headed dog guarding a trapdoor in the forbidden third-floor corridor. Scared out of their wits, the trio runs back to the Gryffindor tower and ponders the dog's presence.
On Halloween, a troll is found in castle. The students are quickly instructed to go back to their common rooms, but Harry and Ron sneak off to find Hermione, who is unaware that a troll is lurking in the castle. They accidentally lock the troll in the girls’ bathroom where Hermione is situated. Fortunately, the three of them manage to defeat the troll. And when Professor McGonagall sees them, Hermione tells a lie to keep Harry and Ron from being punished.
At Harry’s first Quidditch match, his broom goes out of control. Hermione notices Snape staring at Harry and suspects that he is the one responsible for the curse. Stealthily, she sets Snape’s clothes on fire and Harry regains control of the broom, catching the snitch to win the Quidditch match.
On Christmas, Harry receives his father’s invisibility cloak from Dumbledore. He explores the school at night and discovers the Mirror of Erised, which shows the deepest desire of whoever looks in it. When Harry looks in it, he sees his parents smiling at him.
After Christmas, Harry, Ron, and Hermione discover the connection between a break-in at Gringotts and the three-headed guard dog. They learn that the dog is guarding the Sorcerer’s Stone, which is capable of providing immortality to its owner and belongs to Nicolas Flamel, Dumbledore’s old friend.
A few weeks later, Hagrid wins a dragon egg in a game. Since it is illegal to own dragons, Harry, Ron, and Hermione contact Ron’s older brother, Charlie, who studies dragons in Romania. They make an arrangement to ship the dragon but get caught, which leads to a punishment that makes Gryffindor lose 150 points. Part of their punishment is to go into the Forbidden Forest with Hagrid to find out who has been killing unicorns recently. In the forest, Harry encounters a hooded man drinking unicorn blood. The man attempts to attack Harry, but Harry is saved by a centaur who tells him that his attacker was Voldemort. Harry also learns that Voldemort has been trying to steal the Sorcerer’s Stone.
Harry resolves that he must find the stone before Voldemort does. He, Ron, and Hermione sneak off to the forbidden third-floor corridor. They get past the guard dog with the use of a flute, lulling it to sleep. They open the trapdoor and jump. They find out they landed on Devil's Snare, a deadly plant. Trapped in its tentacles, they were short of breath, but Hermione managed to escape and helped them by using fire. The trio continue and end up in a room full of flying keys, one of which can open the locked door at the end of the passage. They find broomsticks and use these to catch a key that opens the door. The next chamber is a large chessboard. To pass this, they have to play the game. Ron takes the place of a knight and Harry becomes a bishop. Hermione chooses to be a rook. Ron sacrifices himself to win the game and becomes unconscious as the queen crushes him. With only two of them left, Harry and Hermione forge on and find a room full of bottles. They pick up a piece of paper with a rhyme that gives them clues. To be able to go to the next chamber, they have to choose one bottle and drink it. Luckily, they pick the right one. Harry instructs Hermione to return to Ron and call Dumbledore for help. Taking a deep breath, Harry drinks the potion and enters the next room.
To Harry's immense surprise, he finds Quirrell. Knowing that Harry wants to find the stone, Quirrell places Harry in front of the Mirror of Erised and makes him say what he sees. Harry sees himself with the stone in his pocket, and at that same moment he feels his pocket become heavier but he tells Quirrell that he sees something else. A voice tells Quirrell that the boy is not telling the truth and requests to speak to Harry. Quirrell then removes his turban and reveals Voldemort’s face on the back of his head. Voldemort, who is inhabiting Quirrell’s body, tells Quirrell to kill Harry, but Quirrell is burned by contact with the boy. A fight ensues but Harry passes out in exhaustion and pain
.
When Harry regains consciousness, he is in the hospital with Dumbledore. Dumbledore explains that he rescued Harry from Quirrell just in time. He adds that he and Flamel have destroyed the stone. Harry goes to the end-of-year banquet, where Slytherin is celebrating its seventh consecutive win of the house championship cup. Dumbledore gets up and awards points to Gryffindor for the feats of Harry and his friends, winning the house cup for Gryffindor.
Later, Harry returns to London to spend the summer with the Dursleys, thinking of ways to make fun of Dudley.
