Last Plane to Avalon — William G. Tolliver

In this third of a series of Arthurian adventures set in the present and using modern characters, Professor Rhod Evans has reluctantly accepted the mantle of the Pendragon. Now, in his final quest, he must travel beyond time and perhaps beyond death. He must take Arthur's place at the Battle of Camlann, to face Mordred on his own turf to end Mordred's evil where it should have ended fourteen centuries ago -- and perhaps to suffer Arthur's fate as well.