The itinerary starts on the same path as its easy and intermediate variants but, from Le Crêt, you'll descend to Maubuisson, then to the Château at Quaix-en-Chartreuse.

Take your fill of drinking water in the village before climbing the Pont de Vence.
Save some breath to rejoin the blue trail at Le Fa.
There are two there-and-back variants: one to La Pinéa and another to l'Ecoutoux from the Brens pass, to enjoy a magnificent view from the top.