The earthquake collapsed one of the walls of a castle. Some people volunteered to clear the rubble, and they discovered a skeleton imbedded in the collapsed wall.
They thought someone was killed and hidden in that wall many years ago. However, one of them thought that someone had discovered the secret to walking through walls, but was unable to master it.
One night, he returned to the castle. After hours of search, he found the book that held the secret.
He started to read it with his torch light, when another wall collapsed upon him, burying him under the rubble.