Cod have become so scarce that there is nothing to make fish fingers from. The boys manage to poach one and raise it to become a giant. But things get difficult when Graeme decides it's his "baby" and he doesn't want to eat it.
The boys set up a bogus Tour company to make money, but their scheme is jeopardized when a Detective's Club demands a tour. Things get worse when three crooks disguise themselves as the Goodies and kidnap them and the detectives.