This run starts at the Strelapass, which you can access either by running up from Davos or taking the Parsennbahn funicular railway to Weissfluhloch followed by the Parsenn to Strelapass
trail. From Strelapass, you'll have a great view of Davos in front of you and the valley behind you through which this trail travels.
From Strelapass, you'll drop into the Haputertällibach valley on a steep, earthen-base singletrack with lots of hairpins. Beware as part of the trail has been washed out. Ford or cross the small bridge over the Haputertällibach creek at the bottom of this descent. Then you'll follow a relatively level, gravel-base singletrack just above the Haputertällibach creek for a little less than a mile.
After that, the trail becomes a gravel doubletrack which descends steeply most of the way down to the village of Langweis. About 1.5 miles before Langweis, you'll enter a forest towards the end of the valley. Follow the Kantonsstrasse road to the center of Langweis.
A number of other routes pass through Langweis. There is also a train station in Langweis, so conceivably you could take the train back to wherever you need to get, avoiding the need for a big climb. Instead, try the Langwies to Strassberg
trail following the Durannapass
loop which takes you back towards Klosters and Davos over a pastoral mountain pass and a remote alpine lake.