Family Portrait, also titled "Picture of Evil", is a novel written by Graham Masterton. It was first published in 1985.
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They found the first body in Europe... She had once been a pretty, fresh-faced girl—but with exquisite skill someone had carefully teased the skin entirely away from her body. She had been skinned alive!
The second blood-raw corpse turned up in New England... And then another—this time uncut, but convulsed with writhing maggots.
Family Portrait. For generations it was was guarded in secret—but as its surface flakes and crumbles a terrible force is reawakened.
And the fate of those who come in contact will be the worst thing in the world.