Mark Chadbourn 
The Hounds of Avalon 

The Hounds of Avalon are coming… For these are the twilight days, when eternal winter falls and the gods destroy themselves in civil war… when an invasion force of ghastly power threatens to eradicate all life. Humanity’s last chance lies with two friends, as different as night and day, but bound together by an awesome destiny. Hunter: a warrior, a rake, an assassin; Hal: a lowly records clerk in a Government office. They must pierce a mystery surrounding the myths of King Arthur to find the dreaming hero who will ride out of the mists of legend to save the world. But time is running out, for when the Hounds of Avalon appear, all hope is lost…