77 Shadow Street by Dean R. Koontz

Welcome to the Pendleton. Built as a tycoon's dream home in the 1880s and converted to luxury condominiums not quite a century later, the Gilded Age palace at the summit of Shadow Hill is a sanctuary for its fortunate residents. Scant traces remain of the episodes of madness, suicide, mass murder - and whispers of things far worse - that have scarred its grandeur almost from the beginning.

But now, inexplicable shadows caper across the walls, security cameras relay impossible images, phantom voices mutter in strange tongues, not-quite-human figures lurk in the basement, elevators plunge into unknown depths. With each passing hour, a terrifying certainty grows: Whatever drove the Pendleton's past occupants to their unspeakable fates is at work again. As nightmare visions become real, as a deadly tide begins to engulf them, the people at 77 Shadow Street will find that they hold the key to humanity's future... if they can survive to use it.