This is unlockable after:
First off, if you do not have a bucket, there is one outside to the right of the door that says "Press to leave Garden" and the locked big metal door. Pick it up. (You might gave to use the door that says "Press to enter Garden" if you are not in that outside screen already which is available to go through at the "Back of the Mansion".Assuming you are starting in the guest house (in front of the fire place) where you unlocked the Give Them a Hand achievement, walk all the way right and leave the house. Run right to the door that says "Press
to go to front of Mansion." Go through it.
Then, keep running right until you reach a well. Press
to use the bucket on it. Then, press
again to enter the well. Keep going all the way down with Flying Hawk stopping you once or twice. Eventually his soul will fly out and enter his body. Achievement unlocked