While doing research in an old university library, Jaan-Mikael (Jami) Warrington comes across an obviously-misfiled book. On first inspection, it purports to be a book of magic, but later turns out to be a chronicle (or foreshadowing?) of events and people who don't appear in any history books.
On a subsequent visit, Jami meets the book's self-appointed guardian and eventually learns that he is one of the historical figures in the book. Only not here and not now.
The book is a sort of portal and eventually draws an unwilling Jami into a place that might be England at a time which corresponds to the early thirteenth century. Jami learns that this world, like his own, is only one of a multitude of Possibilities, each very real to its own inhabitants. But in this Possibility, as in some others, a suspension or alteration of physical laws permit the existence of what Jami would call magic. Magic, however, is rare, and those who use it are not held in very high regard.
What is legend in Jami's own Possibility is real here, and vice-versa. Most disturbing, however, is the fact that the Possibility in which he now finds himself and the one he calls home are linked so intricately that what happens in the one may have dire consequences in the other. And there is a Force here which would like to make that possibility a reality. Of course, Jami is supposed to do something about all this. Only he has no idea what. Making things more difficult is his propensity to slip from one Possibility to the other at the most inopportune moments. Then he finds himself doing the same thing with his other persona. There will indeed come a time when he's not sure who he really is or where he really belongs.
Jami is aided (at times) by the wizard Caliban, apparently the inspiration for Shakespeare's character from The Tempest; the book's guardian, a member of a race known as Thwarts; and a farm girl gifted (or cursed) with the Sight. Their foes are legion…
