We start at the Bellevue Cable Car mountain station above Les Houches. As you exit the cable car station you will see a trail turning left in a eastern direction. This is the gentle sloped path that will take you to Col du Mont Lachat. This is an option you can use but the more spectacular route we suggest takes you over the Mont Lachat summit first. So skip this first path and head passed the Chalette Buvette and then directly turn left and head in an eastern direction to Mont Lachat. This trail starts gentle but then turns into steep zigzags as you climb up to the grassy summit of Mont Lachat. From here take the path to your right that takes you down to the Col du Mont Lachat and the Tramway du Mont Blanc train station. You will see the Col du Mont Lachat trail markers and you should then follow the sign for the direction of Les Ruines. This brings you onto the trail that will take you all the way up to the summit of this trail. On the way you will pass stone ruines marked by a sign. Keep following the path up and use the yellow markers and yellow paint dots to make your way through the boulder fields. You will also be passing by technically tricky spots with supports, ropes and a long ladder. Eventually you wil reach the summit of this trail and a plateau where you will visibly see the Baraque Forestiere des Rognes. Head to the baraque. This is a great place to take a break after your long climb. From the baraque head down and in a western direction. At the end of the descend you will reach a junction. The path north will take you to the Nid d'Aigle train station but you want to take the path going south towards the Refuge du Nid d'Aigle. The refuge is a great place to stock up on water and enjoy a meal or a snack. From the refuge you will see multiple paths leading down the slope in front of the refuge in a southern direction. You want to join the paths that lead south and west down the mountain. The two main paths leading  in that direction will merge and then become  a single track that leads west and then turns into a northern direction along the moraine of the Bionnassay glacier. The path starts out quite steep but then flattens out as you reach the wide valley at the bottom of this plateau. Eventually you will reach a junction where you will want to continue north towards Bellevue. Follow this path in a north-western direction until you reach a junction where you have to turn to the right and go up the hill towards Bellevue. You will pass by the train tracks and continue north until you reach your starting point at the Bellevue cable car.