An American fighter jet is discovered in Scotland's Firth of Clyde. It appears to have been there for centuries, but that is impossible.
American Navy Lieutenant Alex MacNeil is interviewed by Lindsay Pawlowski of the London Times about the plane. Then, with Lindsay aboard, his jet crashes after passing through a fiery vortex. On the ground, they encounter men wearing armor and bearing swords.
To stay alive, Alex and Lindsay must take care. Lindsay disguises herself as Alex's squire as they learn to live in the Scotland of Robert the Bruce.