It is the 1920's: Rival tug fleets compete for work in Bigg City Port. Captain Star briefs his Star Tugs - he's trying the regular contract to dock The Duchess ocean liner. It'll be a difficult job but to help out, the captain has recruited Sunshine, a small switcher. The rival Z-Stacks are encouraged by their devious Captain Zero to sabotage the operation. Their leader Zorran runs Big Mac aground, and nudges Sunshine into The Duchess's bow, swinging her dangerously. Captain Star orders Sunshine's dismissal, but he runs away, and is lost in the harbour in a thick fog.