The Z-Stacks must share the up-river jobs with the Star Tugs. When a tramper that Zorran and Zug are towing goes out of control blocking the river and trapping the Stars, Zorran tries to take advantage of the situation to get more work for the Z-Stacks. However, Zorran's scheme does not go as he planned.

An old dirty tramper from Australia suspected of smuggling lurks outside the limits of Bigg City bay. It is the notorious Johnny Cuba. When bad weather suddenly comes, he forces Zebedee, one of the Z-Stacks, to tow him into the safety if the harbour and into hiding. Normally, Zebedee would have been glad to help out an old friend but this time - things are different.