From a start door, climb a ladder next to a start door.
After you climbed, go toward to the left and get a key.
Swallow a wooden box placed on the left of a door and make a step to go up to the upper right bricks.
Two wooden boxes are needed, so arrange boxes well.
After you got to the upper, move two boxes to go up the upper left brick floor.
Then go along to the left after you can get to the upper, and down to the lower from the left-side edge.
You will find a wooden box there.
Bring it under a ladder.
Climb a ladder to a goal door but this ladder will vanish.
Hurry up.