Chambered (The Bureau, #10)

Agent Dash Cooke likes simple assignments: annihilate the dangerous monsters and move on. He likes a simple life too: a furnished apartment that he switches out for a new one every few years and no messy personal connections.

Then his boss gives him an assignment that's not simple at all.

Reports claim that a beautiful old house in Sacramento is haunted by a poltergeist, but Dash soon discovers a very different type of spirit. Henry will be destroyed if Dash evicts him. And suddenly Dash's life has become very complicated indeed.