It was a warm summer day in 1951 when Rose Rita Pottinger and Mrs. Zimmermann entered the tunnel. When they emerged, it was snowing... and the year was 1828. Mrs. Zimmermann had felt that the ghost of Granny Wetherbee, who had taught Mrs. Zimmermann witchery, was in trouble and needed help. So she and Rose Rita had traveled to Pennsylvania where Granny had lived. They never dreamed that they would also journey back to a time long ago where they would encounter a sorcerer more terrifying than either could have imagined.

The Ghost in the Mirror (1993), by John Bellairs and completed by Brad Strickland, is the fourth book in the Lewis Barnavelt series.

"This book has an extremely propelling plot, and is narratively well written -- from the get go it is humane and clever dialogue and fluid, dynamic prose." - Evan Scott Bryson

She turned helplessly this way and that, but the rows of tombstones stretched on in every direction. She wanted to run, but the grave markers were so thick, they threatened to trip her. She tried to walk between them. She stepped on a low mound, a snow-covered grave, and to her shock she heard a muffled voice below her feet: "Who is that up there? I want company!"

With horror she felt the earth heave beneath her, as if something were burrowing up toward her like a monstrous mole. She ran, her weak ankle stabbing with pain. Mocking laughter echoed all around her. She looked over her shoulder. The graves were all erupting! Bony arms thrust upward everywhere, lashing around and scrabbling. Other graves were wide open, and skeletons clad in rotting clothes were hoisting themselves out of the ground, turning their horrible dirt-caked grins in her direction. The closest ones reached for her legs and tried to trip her.

The black mongrel dog came running behind her, snarling, its eyes glowing a fiery red. Liquid fire drooled from its black lips. Rose Rita tripped over a stone and stumbled. She landed sprawling facedown, her nose crunching into the stinging snow. Instantly cold, icy, skeletal fingers closed over her arms and legs, and the awful smell of decay filled her nose. A gritty, dirt-clogged, cackling laugh burst from the skeletons. The dog wailed and howled close by. The skeletons picked her up, her glasses fell off, and Rose Rita felt herself being tossed through the air. She saw that she was being thrown into a gaping fresh grave. Moonlight touched the marker at its head. The words "HERE LIES A SPY" were carved into it. It was the last thing that Rose Rita saw before she passed out.