Guardians of the Flame: To Home and Ehvenor (Guardians of the Flame Novels (Raen))

When it all began, it was supposed to be a fantasy role-playing game. But a real wizard intervened, and seven collage students were fighting for their lives in a world where magic was real. Years later, Jason Cullinane, son of one of those students, has taken up his mysteriously vanished father's role as baron when reports reach him of an attacking wolfpack of creatures who seem more than wolves. Investigating, he and his comrades find a rift into another world from which evil begins are entering to kill and conquer. And the greatest danger to the band may come from one of their own who has seemingly turned traitor...