Twenty years ago three young boys staggered out of an old building, tired and dirty yet otherwise unharmed. Missing for a weekend, the boys had no idea of where they'd been. But they all shared the same vague memory of a shadowed woodland grove and they swore they'd been gone for only an hour. When Simon returns to the Concrete Grove to see his old friends and unearth painful memories from his childhood, things once buried begin to claw their way back to the surface.