SOLVED. Sci-fi read approx 1986. Teenage boy kidnapped. Final scene in a nuclear power station summoning a demon. Spoilers ahead. [s]

[Richard]

Read to me at the age of 11 by school teacher. Set in English county side, a young boy is kidnapped by a secret group trying to summon demon in a nuclear power station. Floor becomes clear with demon trying to escape during human sacrifice

[Lobstergirl, au gratin]

For kids, teens, or adults?
Author's gender?
Cover?

[[deleted user]]

Sounds like Raven's Gate. Matt is fostered in Yorkshire but it turns out they want to use him in some sort of ritual to summon a demon. Ritual takes place in nuclear power station and the floor becomes transparent.

[Robert]

An amended version of The Devil's Door Bell, since (if it's right) that would have been the one you came across in the 1980s.

[Richard]

Thanks all. Ravens Gate sounds a perfect match.
I’ve ordered the series (wasn’t even aware of the other titles!)