Leif and his cousin Dana have been best friends forever. When they get the news that Dana is moving away, they decide to keep in touch via email. Dana emails Leif to talk about weatherforecasting, her favorite hobby, and Leif emails Dana with news of his pet fish. Leif is excited to learn that Dana's new house has a fish pond outside, but Dana says that the fish seem to be sick. Inspired by the wind turbines of Denmark, Leif and Dana realize they might be able to use wind energy to help solve the problem. Enlisting the help of Leif's mother, a mechanical engineer, Leif and Dana design a windmill to save the fish.