It all starts the summer after Neely finishes fifth grade. She is trying to entertain her little brother, Grub, when they accidentally find a way to sneak into Halcyon House, a magnificent mansion that has been deserted for years. Inside they discover a wonderful surprise - a playroom full of fabulous old-fashioned toys. Despite the spookiness of the house and the rumors about a ghost that haunts it - and despite the fact that they don't belong there - the playroom becomes their secret hideaway. Then the owners suddenly return to Halcyon House. Neely befriends Curtis, a boy her own age whose wild boasts and black moods make her uneasy. When Neely is warned to protect her little brother, she thinks first of the ghost - or could there be a present-day evil lurking in Halcyon House?