The doctors are back! In the first programme of the series, the team bring you the definitive answers to questions including how to avoid losing your marbles and Michael Mosley's tips to cure cramp. Dr Saleyha Ahsan shows how to spot the signs of a deep vein thrombosis, Dr Chris van Tulleken reveals the shocking truth about what is actually in herbal supplements sold in the UK, and surgeon Gabriel Weston travels to the US to witness an astonishing new treatment that could cure crippling back pain for millions of people.