British marathon swimmer Beth French sets out to swim across seven of the world's most dangerous sea-channels - an official challenge called Oceans Seven. For extreme swimmers, it’s the ultimate test; very few people have ever completed it. But driven by her desire to set an example for her autistic son and by her life-long battle with a debilitating illness (M.E. a.k.a. Chronic Fatigue Syndrome), Beth aims to become the first person in history to swim all seven in one year. Traveling to far-flung corners of the world, she confronts jellyfish, sharks, wild weather, mind-numbing fatigue and hypothermia, as well as her own inner demons.