secret door at the bottom of a well, monks involved

An American teenager who is obsessed with Hong Kong cinema and kung-fu classics makes an extraordinary discovery in a Chinatown pawnshop: the legendary stick weapon of the Chinese sage and warrior, the Monkey King. With the lost relic in hand, the teenager unexpectedly finds himself travelling back to ancient China to join a crew of warriors from martial arts lore on a dangerous quest to free the imprisoned Monkey King.

It's the 1940s, and the notorious Axe Gang terrorizes Shanghai. Small-time criminals Sing and Bone hope to join, but they only manage to make lots of very dangerous enemies. Fortunately for them, kung fu masters and hidden strength can be found in unlikely places. Now they just have to take on the entire Axe Gang.