The Lad With the Silver Button: Through the Island of Mull
A "ross" is a peninsula (i.e., a piece of land surrounded on three sides by water), and the Ross of Mull is a specific southwestern part of the island of Mull (source).
This is where Davie winds up when he crosses the dried-up creek. It's not an area he's at all familiar with – the only landmark he knows is the hill called Ben More.
Davie walks towards the line of smoke he saw from Earraid.
This leads him to a house where an elderly man is sitting outside. Davie finds out that the crew of the Covenant also made it to this very house the day before, and that one of them was wearing breeches and stockings (i.e., was dressed like a gentleman).
This gentleman – Alan Breck, reasons Davie – has left a message for Davie ("the lad with the silver button" (15.7)). The message is that Davie should follow Alan to his country by way of the town of Torosay.
Davie then finally gets a good meal and some strong spirits that cure his sore throat.
He reflects on the elderly man's great manners, thinking that "if these are the wild Highlanders, I could wish my own folk wilder" (15.13).
As Davie walks out to follow Alan, he observes the habits of the people around him. Remember, this is all in the wake of the Jacobite rebellion, which was also an uprising of the Highland clans against the current English king.
To clamp down on their patriotic feelings, the English government has forbidden these people from wearing kilts or any kind of traditional clan markers.
The people Davie passes handle this law from their conquerors by either not really wearing clothes at all or by wearing a philabeg (a Highland word for kilt) and stitching it down the middle so that it's a kind of skort instead of a proper skirt. They're very poor, but proud too, and they speak (or are willing to speak) little or no English.
Davie does manage to find a guide who'll take him to Torosay. The guide's a bit of a cheat, and Davie has a hard time getting him to stay sober and alert enough to make the journey.
The guide keeps pretending to forget his English just long enough to force Davie to part with a little more of his money. Davie finally loses his temper, and they get into a physical fight. The guide gets out a knife, and Davie manages to steal both the guide's knife and shoes.
Davie continues alone along the way for half an hour, until he runs into a blind man. The blind man claims to be a "catechist" – a lay religious teacher. Davie finds this hard to believe, since the guy's face seems so secretive and dishonest.
Another thing that's weird about the blind man is that he's carrying a pistol, which (a) is currently illegal in the Highlands, (b) seems odd for a religious man, and (c) appears really impractical for a person who can't see.
Still, Davie agrees to let the man guide him to Torosay in exchange for a bottle of brandy. The blind man says that he knows every rock of Mull well enough to get around with just his stick as a guide.
The blind man also tells Davie that, before it became illegal to carry a pistol, he was a great shot, even though he can't see. The blind man appears unaware that Davie can see the man's pistol butt sticking out of his pocket, and Davie's getting more concerned by the minute at his new companion's apparent violent tendencies.
The blind man clearly starts feeling Davie out to see how much money he has, and Davie finally gets so creeped out by his obvious intent to rob him that he tells the blind man he's got a pistol of his own and will blow his brains out if he doesn't go away.
The blind man curses Davie in Gaelic and eventually goes off on his own across a bog.
These two men, the guide and the blind man, are the worst Davie meets in the Highlands.
At Torosay, Davie finds an inn kept by a gentleman of the Maclean family, who speaks great English, excellent French, and okay Latin. He doesn't know Alan and doesn't think much of Ardshiel's clan in general. But he does like Davie.
The innkeeper tells Davie that he got off lucky with the blind man, whose name is Duncan Mackiegh. He's a well-known highway robber who has even committed murder.
Davie finally goes to sleep, feeling pretty good about himself. He's travelled nearly a hundred miles of road in the past four days, and he's in great physical shape.