The survey should have taken two weeks. Map the rooms, measure the walls, photograph the details. Zechariah Wormwood's 1887 estate was being converted into a luxury hotel, and Jackson Hewitt was hired to document every square foot before the contractors moved in.

The Keep was built from imported gray quartz. Railroad money. Wormwood was famous for his philanthropy. Took in destitute women and children. Gave them shelter, food, a second chance.

That was the story, anyway.

On the third day, Jackson's measurements stop adding up. The interior dimensions don't match the exterior. There are spaces behind the walls that shouldn't exist. Gaps that the original blueprints never showed.

His assistant Carla finds the first hidden room behind a panel in the east wing. Restraints bolted to the walls. Scratch marks in the stone. A surg ...