Eric Olthwaite is so boring that his family all leave home to escape him. Then one day he is accidentally caught up in a bank robbery and discovers that the robber shares his interests in shovels, black pudding and rainfall so they team up to make daring raids to steal rainfall records. As a result Eric becomes famous and is considered interesting again, so much so that he is made the mayor of Denley Moor.

The Goodies fall on hard times, and Tim and Graeme send Bill to sell their trusty three-seater trandem. All the local townspeople find it ridiculous and Bill is humiliated by only being offered a tin of baked beans. Tim and Graeme are disgusted with only getting baked beans, instead of money, but Graeme gets the idea to plant a bean. This rapidly grows into an enormous beanstalk - reaching all the way from England to the summit of Mt. Everest. In hot pursuit of their beanstalk, the Goodies enter an "It's a Knockout" competition, which is being held at the foot of Mt. Everest. Among other things, the Goodies have to climb the beanstalk to the top of the mountain, as part of the contest. There, they find the Giant's castle and, in it, a Giant of surprising height who has a valuable secret to protect.