From a start door, go to the right as long as a row of seven ladders.
Climb the third ladder from the left; there is a key at the top of the ladder.
After you got a key, go back your way to the left and climb the right-side ladder of two lined.
After you climbed it, climb again a ladder on your right.
When you get to the top of a ladder, there are a large amount of wooden boxes and bricks on your right.
Swallow a wooden box from them and go to the left edge.
Release it under a ladder on the left-side edge to climb it.
You can find a wooden box on your right after climbed.
Swallow and drop it into a trap hole on your right.
Then go toward the right to reach a goal door.