The doctors take on their smelliest investigation yet when they find out how the shape, size and pong of your poo can tell you a lot about your health! Dr Xand visits the largest blood factory in the world and donates his blood to see how it is processed to help save lives. And Dr Chris spends time with the Midlands air ambulance crew; an awesome airborne emergency service which can get to the scene of an accident quickly. Meanwhile, over in accident and emergency, one patient has been admitted with a deep cut to her hand after slipping on some glass and another has to have a gash on his head glued together after crashing into a tree stump.