The Diabols by R.W. Mackelworth
Paperback Library, 1969
Originally published as Firemantle, Robert Hale, 1968
Price I paid: 75¢
Their bodies were colored lights; their voices were music. But whatever they touched was incinerated!
For a moment in time their destructive powers were limited to a small portion of Earth. Yet they were determined to burn the whole planet to a crisp.
Was there no hope for man’s survival?
As a last resort Boraston is projected into a future where the Diabols have almost won. Only a few humans remain, struggling to stay alive by holding the Diabols off with skirmishes and holding actions.
Can Boraston devise a method to destroy them?
If he succeeds, Earth can plan to save itself from the Diabols.
If he fails, Earth was doomed to become nothing more than a charred and blackened cinder in the galaxy!