The plot of every story for children since the 1980s. Or earlier.

The protagonist is a normal __-year-old, where __ is anything between ten and nineteen (occasionally out of that range, such as in The Hobbit or The Lord Of The Rings, in which the protagonist is 50). He (usually he) is removed from his home, usually because his guardians (parents are unknown) have died or vanished without trace, so he has no choice but to go with this mysterious older person, who takes him either to a secret society of others just like him, or to a completely unfamiliar place in severe trouble. In the first case, before long, he finds out that unusual events are taking place, and that the society will soon be in trouble. In the second case, he is attacked immediately after arrival. Either way, he goes on a massive quest, which will result in him making a small group of good friends (no more than three or four) and a slightly larger group of people who are less significant to the story. Some of the second group will inevitably die in a huge battle near the end of the story. There is also a mega-villain who is killed at the end of the story, and his second-in-command is forgiven for his wicked actions before (usually) dying.