The date was April 17th 1945 and the battle for Berlin raged through northern Germany. But a British ambulance unit was diverted from the frontline to handle an unfolding medical crisis. The liberation of Belsen did not bring an end to the death toll. Instead, it was the start of a humanitarian catastrophe. 40,000 prisoners were trapped in a man-made camp of indescribable squalor; deprived of food, clothing and basic medical care. In the space of one month an international team of doctors and nurses battled against logistical hurdles and administrative red tape to save thousands of lives and build the largest hospital in Europe.