Nina ("Nine") Tanleven and her best buddy Chris Gurley are having a hard time. The play that led to them meeting a ghost and unraveling a mystery has ended. Now the rest of the summer looms ahead, looking dull after their great adventure.

Luckily, Nine's dad gets a job designing the restoration of an old—and distressingly run down—hotel in the Catskill Mountains. Nine and Chris are more than happy to tag along … and even happier (if also slightly terrified) when it turns out that the Quackadoodle Inn is haunted. Who is the handsome ghost in the Confederate uniform who keeps appearing to them … and what unfinished business holds him to the inn?

As the girls work to unravel the mystery of the Quackadoodle, they uncover a compelling story—a story that can only be completed by a dangerous midnight effort from the intrepid young ghostbusters!