In a middle school at the foot of Mont Blanc, SEGPA students have no interest in anything. To motivate them and make them dream, Alain, their teacher, organizes a surprising and perilous outing into the bowels of a glacier. The teenagers discover a breathtakingly beautiful world of ice. But they realize that with global warming, if nothing is done, this glacier like many others could disappear. Against everyone's advice, but led by their teacher, they throw themselves heart and soul into a crazy project: to protect the glacier and stop it from melting... From now on, nothing can stop them, because there's no Planet B!