It was there again, that sudden hint of depth in the heart of the bookcase’s shadow. This time, before he could regret it, Paul reached out to touch the wall. Instead of rough plaster, his fingers sunk into a cool wet darkness and he jerked backwards, stumbling over the couch. His pained yelp as he hit the floor brought the dog running, and the two tangled for a moment as he got to his feet. After ensuring that his fingers were still there, and that the slick wetness of the shadow had remained safely on the far side of the wall, Paul cautiously approached the bookcase. The feeling of depth was still there, and he could see a faint ripple running along the shadow as if he had disturbed the surface.
At his feet, Blazer snuffled his shoes, ignoring the distinctly improbable shadow. Paul took this as a good sign, since the white and black mutt had an overprotective nature. If she thought squirrels, blue jays and vacuum cleaners were more dangerous that the inky darkness, it ought to mean he was safe.