Documentary following the stories of three patients being treated for cardiac problems at St George's Hospital, south-west London. Corey has suffered cardiac arrest while playing ice hockey, prompting doctors to keep the 24-year-old in an induced coma to prevent further damage to his brain. At almost 60, Angie has a history of heart disease and her heart has been beating at over 150 for eight hours, risking stroke and other complications. Doctors also carry out tests on 49-year-old Steve to determine the cause of his dangerously high heart-rate.