Bert and Nan -- the older Bobbsey Twins -- and their lively young sister and brother twins -- Flossie and Freddie -- find themselves involved in a breathtaking series of adventures in The Bobbsey Twins at the Ice Carnival. In gratitude for the Bobbsey family's kindness after her house burned, Mrs. Kape, their neighbor, invites them to visit Fairy Lake to attend an Ice Carnival, where the twins take part in all of the festivities and solve a mystery.