The Trespassers — Zilpha Keatley Snyder

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?Zilpha Keatley Snyder's mesmerizing characters and vivid details will pull readers into an everyday world charged with mysterious menace in this suspenseful, haunting story.From the Hardcover edition.