Because to his associates he is known as the Boogeyman. No not because he is the boogeyman but rather when you want to kill the boogeyman you call him!!!
John Wick is an assassin who is feared and respected by all. After five years he is forced out of retirement to enact revenge upon those who have taken everything from him.
The movie is action packed given the fact that its directed by stuntmen David Leitch and Chad Stahelski who have done several stunt work in major movies including the Matrix Trilogy. This is probably why the movie has virtually no story. But nevertheless it is a must watch for all action movie enthusiasts.