From the Nature Park Information Center in Scharnitz, follow the Hinterautalstraße about 2 km into the valley, then turn left and hike in several switchbacks to Lablehner. This place, a clearing in the meadow, offers a beautiful view of Brunnstein and the Karwendel Valley.
The path flattens out for a short distance (always keep to the right) and then steadily climbs in numerous switchbacks to the Pleisenhütte, which invites you to take a break on its sunny terrace on the south side. Hikers in good shape can continue the ascent to Pleisenspitze (2569 m).
Just behind the hut, a narrow, partly steep trail initially leads through dwarf pines and later over alpine meadows to Pleisenspitze, which offers a spectacular view of the surroundings. The descent is via the same route. Good footing is required!
For those who only want to visit the Pleisenhütte, there is also a detailed tour description: Hike to the Pleisenhütte.