Escaping from a Confederate prison by balloon, the survivors land on an uncharted island in the Pacific. The island is home to carnivorous monsters, bloodthirsty pirates, and the mad genius Captain Nemo, who inhabits the island for his own strange ends.

This season started by going back to the Highlands of Scotland when Duncan was only 13 years old; we got to see him in close contact with his cousin Robert. Ritchie, now an immortal with no false belief that Duncan will protect him and watch out for him, is ready to take care of himself. Hugh Fitzcairn, Amanda, and Methos make appearances.