Louise Meacham wants in because a fellow CIA agent committed suicide there, and she has to put the ghost rumours to rest to get her career back. Anna Pertwee wants in because she's determined to save the ghosts from the unbelievers and the debunkers. Patrick Hudson wants in because he has to save Gray's soul.
So Gray will let them all in, these people who think they're coming for the truth. What they don't know is that the truth is coming for them.