Full Circle is a gen Star Trek: TOS 180-page novel by Holly Trueblood.
It was an accident of physics that thrust the shuttle and its passengers away from Vulcan into an otherwhere and otherwhen. Spock and his companion found themselves in a long-gone time of myth and majesty: Camelot! Susannah Morgan was well versed in the the legends. But what was the reality? Historians had argued about Kirk Arthur and the Knights of the Roundtable for centuries. Now Spock and Susannah were about to learn the truth and have a hand in its creation. 
In the English language, only one cycle of stories has generated more fan fiction than the Star Trek universe. . . the deeds of King Arthur and his noble knights. Could it be that there is a place where the legendary characters of these two story cycles intersect. . . or in fact be inextricable intertwined? After all, what’s that old saying about any technology sufficiently advanced being seen as magic by those who do not understand it? Mark Twain did it in “A Connecticut Yankee,” but when author Holly Trueblood plays the time travel game with a certain Vulcan scientist, the plot is as twisted as a celtic knot. 
- ↑ from Media Monitor which in turn is from Orion Press
- ↑ from Agent With Style