Jack O'Brian somehow has failed to develop any sense of professional style but he spins a good yarn, and his Silver Chief stories are popular. His knowledge of the far north gives authenticity to his background. This new story of Jim Thorne of the Mountles brings his adventures right up to date, with a blind assignment that turns out to be linked with escaped Nazi prisoners. There's a girl slant this time, in the injection of motherless winsome Pat into the trading post atmosphere. A suggestion that Jim's promotion -- and his taking Pat back home -- mean more to come. This one, however, is routine good adventure.