On Whit Sunday 2014, speleologist Josef Häberle has an accident in the Riesending cave near Berchtesgaden. With a life-threatening head injury, he lies at a depth of over 1000 metres - and over 12 kilometres from the shaft entrance. His climbing colleague Ralf Sommer fights his way back to the surface to alert the rescue services, while two other companions try to keep the injured man alive. The mountain rescue team takes charge from minute one, but without any knowledge of the Riesending cave and without expertise on how to rescue from this depth. Ralf Sommer sees only one chance to save his comrade: a call for help to the international speleology community.