On the day Cassie was born, they drowned her town. The mayor flipped a lever and everyone cheered as Old Lower Grange was submerged beneath five thousand swimming pools’ worth of water. Now, twelve years later, Cassie feels drawn to the manmade lake and the mysteries it hides — and she’s not the only one. Her classmate Liam, who wears oversized swim trunks to cover the scars on his legs, joins Cassie in her daily swims across the off-limits side of the lake. As the summer heats up, the water drops lower and lower, offering them glimpses of the ghostly town and uncovering secrets one prominent town figure seems anxious to keep submerged. But like a swimmer who ventures too far from shore, Cassie realizes she can’t turn back. Can she bring their suspicions to light before it’s too late — and does she dare?