Dan, 37, faces one of the hardest waits of his life. Diagnosed with primary sclerosing cholangitis - a disease that is causing his bile ducts and liver to fail - his only chance of survival is a liver transplant. A potential donor has been found, and now the race is on to assess the liver's viability. Once in surgery, Mr Bartlett works against the clock to quickly remove the old, diseased liver. But while trying to restore the blood supply to the new organ, there's a worrying lack of blood pressure.