Colin MacLeod, the immortal Scottish Highlander seeking vengeance against the merciless Marcus Octavius, who killed his cherished one in a Celtic battle ages ago, embarks on a quest with the sarcastic ghost Amergan. With New York City underwater, only one colossal stronghold owned by Octavius remains visible. MacLeod faces a dilemma: should he save the survivors of the flooded metropolis, or should he focus on tracking down his nemesis?