When Connor MacLeod sees his old friend Rachel die in an explosion, he's had it with his immortal life and the endless pain it brings him and those he loves. He locks himself inside the Sanctuary, a Watcher-organized retreat stationed on holy ground, where immortals who are tired of the game can go to forever escape it, as well as to ensure that The Prize never falls into the wrong hands. But when an old enemy, Jacob Kell, and his posse of assassins attack the Sanctuary and kill everyone there but Connor, he is forced out into the open and into battle. Kell and Connor were friends once, and knew each other back when Connor was cast from Glenfinnan; he returned when news came that his mother was to be burned at the stake, and in the attempt to free her, Kell was killed by none other than Connor himself, and became an immortal, bitter with hate, and devoted to making Connor's life a living hell. In the present day, Connor's kinsman Duncan MacLeod is attacked by Kell's posse, including Kate, an old love of Duncan's who seeks revenge for her unwillingly being made an immortal centuries ago. This attack had something to do with Connor, and Duncan goes in search of him to find out why. In the process, he learns that in the 450 years since Connor and Kell's encounter in Glenfinnan, Kell has taken more than 600 heads and gained enough power to be called nothing less than the most powerful immortal alive. To make things worse, neither Connor nor Duncan are strong enough to face Kell alone.
