There’s a monster in the Nahuel Huapi Lake. In the twilight, it spreads itself out across the surface of the water like a taut cowhide, grasping at its victims with sharp claws. Another monster also lurks in the surroundings of the lake, which is close to Bariloche in the Argentine Andes. It is called Capa Negra: the Black Cape. It haunts the ski slopes by night and should be a...