The Aldens are visiting Aunt Jane in Elmford. She tells the children that she has tickets for them to see a mystery play at the Trap-Door Theater. A theater patron who loved mysteries left her life savings to improve the theater and to hold a yearly contest with a cash prize awarded to the best mystery playwright in town. The Aldens can't wait to find out everything there is to know about the old Trap-Door Theater. But there is more than one mystery

The Aldens visit the upstate New York town where the "Legend of Sleepy Hollow" was set and discover a headless horseman mystery all their own! Their friend's ghost tour business is threatened by a spooky figure on horseback who is throwing gory pumpkins. Who—or what—is haunting Sleepy Hollow?