Dagger of the Mind — Bob Shaw

'The entire head had been stripped of skin, creating a nightmarish sculpture in gelled blood...'
The hideous apparition that confronted John Redpath almost defied description. It was the beginning of a horrific ordeal that would cause him to question his own sanity...
A member of a telepathic research project, Redpath believes the cause to be side-effects from the experimental drugs he is taking - but then stranger things begin to happen. He wakes up to find himself in America...he is drawn to a local house occupied by a bizarre group of people leading an artificial and peculiar life...which events are really happening?
Slowly an explanation emerges, more terrifying than anything he could have imagined...