Glencoe - Chapters 17 - 21
This section (43km) covers the murder scene and the start of the "flight in the heather" through Glencoe.
Here is the crux of the book when David Balfour is accused of being involved in the murder and has to flee for his life from the Redcoats. Allan Breck meets up with David on the hillside and the pair head off into the back of Glencoe to warn the folk there. Then they are almost caught at Signal Rock before hiding out in Coire na Ciche (where the real Allan Breck had also hid at the time).
The route then follows the road to Kinlochleven where you should stock up before heading to Rannoch Moor.