Jack lives with his mother Dame Trott in the town of Banburyshire. Despite living in constant fear of the Giant who lives in a Kingdom in the sky, Jack is still a carefree boy in love with the pompous Baron's daughter, Jill.

When the Baron demands payment to appease the Giant, Jack and Dame Trott are forced to sell their beloved cow Buttercup. Sensing an opportunity to help Jack as well rid the land of evil, Jack's Fairy Godmother gives him five magic beans in return for the cow. Soon the beans grow into a huge beanstalk which Jack vows to climb it in order to steal the Giant's gold and pay his mothers debt. However, he doesn't count on the cunning of the Giant and his evil henchwoman, the wicked witch Poison Ivy, who also happens to be the Fairy Godmother's twin sister.

Not only must Jack keep his loved ones safe from the duo's evil clutches, but he must decide whether the mysterious stranger, Captain Pugsley, and his strange crew of sailors are friend or foe.