Based on a true story, this made-for-TV movie concerns the true story of Marilyn Bell (played by Caroline Dhavernas), a 16-year-old swimmer who found herself competing against Florence Chadwick, a top-ranked, well-known American swimmer in a special marathon race across Lake Ontario. While Chadwick was the more experienced swimmer, Bell stunned the sporting world when she won the race after the American swimmer, underestimating the difficulty of the conditions, dropped out at the half-way point. Heart: The Marilyn Bell Story also stars Claudia Besso and Ron White.