In June 1990, the Navidsons go away for four days and return to the house to find “a strange spatial violation” (24). They discover a door in the master bedroom which opens up to a closet, which in turn has a door opening to the children’s room. Photos show the door was not there before, so Will and Karen find the original blueprint, which show a crawl space that was slated to be constructed by previous owners but never completed.

Will measures the space inside the closet and the exterior of the house and finds that there is a quarter-inch discrepancy. He repeats his measurements six times and gets the same result. Will enlists the help of his twin brother, Tom, whom he has not seen in eight years. Tom is a house builder and finds there is a 5/16th-inch disparity. Will asks his engineer friend, Billy Reston, to lend some more advanced equipment to measure.

During this time, Karen has her friend, Audrie, come over to build new bookshelves for the house.

Using Billy’s Leica meter, Will and Tom find that the measurements match up. However, they then discover that there is a foot of space between the newly-built bookshelf and the wall.