Jack: Lock the Doors. Watch the Roof.

JACK

Lock the doors. Watch the roof.

For thirty years, Calder dismissed Jumping Jack as an urban legend-a masked figure glimpsed on rooftops, a warning whispered after dark.

Then building inspector Nora Keene finds evidence of someone moving through the forgotten spaces above the city.

When a routine inspection turns deadly, Nora discovers that locked doors offer little protection from a killer who knows the buildings better than the people inside them. He climbs where no one thinks to look. He...