After Midori Koto sees her husband, rich industrialist Michael Kent, murder her lover, she kills Kent and runs to MacLeod for protection. She reminds MacLeod of a vow of protection his "ancestor" (MacLeod himself) made 200 years before. Flashbacks tell the story of MacLeod coming to the aid of the samurai Hideo Koto after MacLeod is shipwrecked in Japan. He vows to Hideo he will always protect the Koto family and is bequeathed the dragon head katana sword he uses to this day. Back in the present, MacLeod discovers that Kent is an Immortal and he's still alive.