Speculative fiction is a broad umbrella category of narrative fiction referring to any fiction story that includes elements, settings and characters whose features are created out of imagination and speculation rather than based on attested reality and everyday life. That encompasses the genres of science fiction, fantasy, science fantasy, horror, alternative history, and magic realism.
In an alternate history set in A.D. 865, Shef, son of a Norse raider
and an English lady, tries to carve out a kingdom of his own in
England, while Christian kings and Viking worshippers of Asgard battle
for the country's dominion.