Donald Duck, holding a hunting rifle, passes through a doorway to find that he has entered Mathmagic Land. This "mighty strange" fantasy land contains trees with square roots, a stream flowing with numbers, and a walking pencil that plays tic-tac-toe. A geometric bird recites (almost perfectly) the first 15 digits of pi. Donald soon hears the voice of the "True Spirit of Adventure" (Paul Frees), who will guide him on his journey through "the wonderland of mathematics".