A deadly recipe threatens the survival of countless creatures throughout Earth's oceans. We've known for years that oceans absorb about a quarter of the carbon dioxide in our atmosphere. With carbon emissions sharply rising, the silent killer is entering the seas at a staggering rate - raising the oceans' acidity. As a result, the skeletons and shells of marine creatures that form the foundation of the web of life are dissolving. Follow scientists who are seeking solutions and making breakthrough discoveries, including a unique coral garden in Papua New Guinea that offers a glimpse of what the seas could be like in a half-century. Can experts crack the code of a rapidly changing ocean - before it's too late?