Ian Watson 
Fire Worm 

Psychiatrist John Cunningham is secretly also "Jack Cannon", author of popular horror novels. Under hypnotic regression, John’s patient Tony reveals a bizarre and horrifying tale of a "past life" lived on Tyneside in the 1950s, involving two schoolboys and a weird creature with paranormal powers lurking in caves beneath Tynemouth Castle. As John regresses Tony through earlier lives as far back as the 14th century it begins to seem that the local legend, captured in folksong, of a malevolent Lambton Worm may have had a basis in fact: that it was, in fact, the salamander of alchemical belief, summoned by an alchemist known as Raymond Lully, and possibly still locked below Tynemouth Castle And while John Cunningham is exploring Tony’s multiple personalities, he begins to experience personality problems of his own, as Jack Cannon beings to assert his own individuality.