Alexander Huntley's new beach house has an ocean view, a lighthouse, and something in the walls. Every night, when the beam sweeps past, a shadow moves across the plaster—walking, stopping, watching. No one else is in the room. No one else has ever lived here. But the shadow keeps moving. And when Alexander measures the wall, he finds space that shouldn't exist. The light shows what hides in plain sight. But some shadows don't stay on the wall forever.