The setting switches back and forth between Giron in 1910 and Nome in 1899. I know where Nome, Alaska is. Giron's location puzzled me. Sedgewick tells us only that it's at 68 latitude north. Reindeer are mentioned. Did the author mean caribou? Or is Giron in Scandinavia or Russia? Later, Sig is about to go outside to get more wood for the fire that's died down. Then Wolff comes and Sig must stay put. Hours later, the fire is still going. This is the kind of thing that really bugs me.
Even so, I'd recommend Revolver to anyone, Grade 7 through to adult, looking for a tightly-written psychological thriller. My brother, a fan of Louis L'Amour and spy novels, would love it.