When a fishing guide reels in the body of a young man on the Madison, the Holy Grail of Montana trout rivers, Sheriff Martha Ettinger suspects foul play. It's not just the stick jammed into the man's eye that draws her attention; it's the Royal Wulff trout fly stuck in his lip. Following her instincts, Ettinger crosses paths with Montana newcomer Sean Stranahan, a fly-fisher, painter, and has-been private detective. The clues lead them back to Montana's Big Business: fly fishing. Where there's money, there's bound to be crime.