The Mystery of Gallagher's Ghost

In Book Six of the series, Orvie finds himself in the Ozark Mountains helping a new friend - Joey - solve a mystery involving the haunting of Joey's big old house by a long departed relative who wants Joey and his mother to leave. The ghost - Gallagher - appears at various places in the house and on the lawn. It eventually becomes destructive and kidnaps the boys. The mystery is much more than it seems and they work to solve it and save the house from being burned to the ground. They find that a 'ghost' may sometimes not be a ghost. Even the FBI becomes involved.