After his fifteenth birthday, Blythe Midwinter finds himself in a bit of a pickle. It's high time for him to be a productive member of his family, taking up work he detests in order for his older sister, Molly, to follow her dreams of success as a talented baker. Though the three orphaned Midwinter siblings -- Molly, Bertie, and Blythe -- are lucky enough to work, they still earn only enough to keep themselves clothed and fed. Blythe desperately wishes for more, and it doesn't help that his best and only friend, Jack Wicket, refuses hard, honest work in favor of good luck as the only means for quick success and instant riches.
Blythe's dreams of a better life get more desperate when he attracts the attention of another boy, the youngest son of a rebellious old artist, whose family rises well above Blythe's in wealth and station. Embarrassment and shame muddle Blythe's perceptions of luck, work, and the promise of love -- that is, until Jack Wicket's foolish decision to exchange his beloved cow for a handful of magic beans forces Blythe to look past castles in the clouds and understand what it is that truly measures a man's worth.