The kids are summoned to the Overview Hotel by Jack Marsten, the owner, to rid it of the ghost of Ebenezer Overview, the former owner who died 100 years before. / At the top secret army compound, Codefinger the master spy, steals the top secret government decoder. While on the getaway, he stashes it in Pingree's Department Store. The government recruits the gang to find the decoder named Myrtle, by using code words it responds too, throughout the store.