Nicki is plunged into another mystery when she accidentally takes the wrong suitcase from the airport and finds it filled with bundles of hundred dollar bills.
Nicki and her friends travel to Ireland where they find themselves searching for a legendary treasure that will make it possible for their hosts to keep Cravenhill Castle.
Nicki is determined to solve the mystery at Pine Grove Middle School when a student's research paper is stolen and circumstantial evidence points to her new friend Kim, a Korean American.