In Bigg City Port there are two tugboat companies - The Star Fleet owned by Captain Star and the Z-Stacks owned by Captain Zero. The Stars are honest and hardworking, but their rivals, the Z-Stacks are not to be trusted and often cause trouble. In this story, Sunshine, an up river tug, comes to help Captain Star's team bring a huge liner, The Duchess, into port. But the Z Stacks, led by Zorran, are determined to spoil the Stars' big chance...