3m above Énergie d'Activation, 30m to the right of Le Chemin des Sables du Cul de Chien when going down from the path between the two hills. Standing start at the arete with two low underclings by convention, climb the arete and exit on the right or on the right arete as for Les Mystères de L'Ouest (slightly harder).
NB : 6c without convention at the start.