Doctor Grandjean, an out-of-the-ordinary veterinarian, lately has dedicated his attention to the dogs which accompany the protagonists of great adventures, such as for example sleddogs and rescue dogs. In the movie we see him in Chile, in the Atacama desert (the driest in the world) dominated by a 6000 m high volcano where, with Parisian firemen and Chilean policemen he tests the resistance to altitude of teams of men and dogs during high-altitude mountain rescue missions. It is a difficult experience, which does not end up successfully for all, organised in co-operation with the Sorbonne, the Paris Faculty of Medicine and the Maisons Alfort Veterinary School.