In a sentence: Skinny dude with a funny name gets chased by a headless horseman and dies. Or runs away—unclear. The end.
Here is the (slightly) longer version:
Once upon a time, a guy named Ichabod lived in a little town called Sleepy Hollow. He was the town teacher and choirmaster. In other words, he was pretty important people. That's the backstory and this is where the craziness starts.
One day, Ichabod realizes that the richest guy in town has an only daughter who's pretty good lookin'. He decides that he's going to hit on her so hard that she'll have no choice but to fall in love with him. Flawless plan, clearly. Oh, there is one problem though. There's this other guy named Brom and he wants to kill Ichabod for taking his lady. Minor snag.
Ichabod lies low for a while because, you know, he doesn't want to die, but then something amazing happens. There's a party at his lady's place and he is invited. Booya. He gets dressed up, sprays on his finest Axe Body Spray (19th-century edition), and heads off on his borrowed steed.
The party is hoppin', but when it's over, his lady dumps him. Ichabod is making his way home, crying all the way, when he meets the Headless Horseman. Ichabod goes nuts trying to get away from him, and when he finally thinks that he's safe, the Headless Horseman throws his head at him, and knocks Ichabod off of his horse and onto the ground.
The next day, no one knows what happened to Mr. Crane. They see horse tracks, Ichabod's hat, and a pumpkin, and they all assume the Horseman got him. We hear that Ichabod ran away and became a judge. But Brom laughs mighty suspiciously every time they talk about Ichabod. Hmm, could it be? Nah, it was the Horseman. Right?