Watch Léon: The Professional (1994) Online

If you don't know about Léon: The Professional, you gotta check it out on Hulu.

Or, if you're one of those la-ti-da above-ground dwellers, you might consider buying the DVD from Amazon.

And if you don't know about Léon: The Professional, read up on Wikipedia. But watch out, they've got the whole plot on there. So if you're not into that sort of thing, just be careful not to read the plot synopsis.