The Harry Potter novels take place in [Hogwarts School of Witchcraft and Wizardry]?, a castle in the middle of a ring of mountains, usually accessed from platform 9 3/4 at [King's Cross]? train station, London. While its exact geographic location has not been mentioned in the novels, the descriptions and comments made by the author imply that it is in Scotland.
Each book in the series chronicles one year in Harry's life at Hogwarts. There are supposed to be seven books, each getting a little bit darker than the previous one as Harry gets older.
At Hogwarts, he befriends Ron Weasley, the youngest son of a poor wizarding family, and Hermione Granger, a Muggle-born girl (not of a wizarding family) who is the smartest witch of her age, and develops a rivalry with brat-prince Draco Malfoy.
The main plot revolves around the contents of a forbidden room, which Harry and friends eventually discover contains the philosopher's stone. Using it, Lord Voldemort will be able to resurrect himself from his mysterious death while attacking the infant Harry. It remains for the three protagonists to prevent this.