Based on Mark Twain's stories, this feature-length Claymation fantasy follows Tom Sawyer, Becky Thatcher, and Huck Finn as they stowaway aboard Mark Twain's interplanetary balloon. Twain, dissatisfied with humanity, is hell-bent on locating and colliding with Halley's Comet in order to fulfill his "destiny." Tom, Becky, and Huck must persuade him that his judgment is incorrect and that he still has plenty to offer humanity that may make a difference. Their actions are not merely charitable; they risk sharing Twain's fate if they fail. Along the journey, they utilize a magical time portal to gain a thorough understanding of Twain's philosophy by watching the "historical" events that inspired his works.