The last member of Bly's gang, a cat-burglar named Pepe Bendrix, escapes Bowler and Brisco but is arrested by Agent Brown, who offers him a pardon in return for Pepe's recovering the last Orb. Meanwhile, a time traveller, Karina, arrives and tells Brisco that the Orbs are artifacts from the future.

Brisco is assigned to transport an English spy, Emma Steed, to Mexico as part of an exchange. Trouble arises when it turns out there is an assassin aboard the stagecoach, sent to make sure Steed doesn't get to her destination.