Merry Cruesdnam is a very sick 10-year-old little girl, confined to her house because of severe, uncontrollable anxiety and physical illnesses that cause seizures and death-like paralysis without warning. She has turned the attic of her family's home in the small New England town of Usher into her private playroom and living quarters. Because of her condition, she spends many hours watching the children run and play, wishing she could join them.

When she meets her neighbor, Bagston Lewy, the two children quickly form a strong bond, and within weeks, they are inseparable. Bagston visits Merry every afternoon after school, and he joins Merry in her fascinating imaginary world she has created in her spacious attic room.

However, as Bagston finds out, things are rarely as they seem in that attic, or with Merry, and seeing is just the beginning. And years later, when a serial killer strikes in Usher, Bagston, now 30, works with police to uncover the killer's identity. He gives authorities every detail he witnessed as he watched the gruesome crimes take place from the same attic where he and Merry played until she died. But will Bagston's witness reports be enough? Or is there something far beyond the surface that, when it unravels, will shake the foundation of Bagston's reality forever?