Once a police detective in St. Paul, Minnesota, Rushmore McKenzie, after becoming an unexpected millionaire, now is an unlicensed private investigator, doing the occasional investigative favor. Off on a weekend getaway to northwestern Wisconsin, McKenzie, with a group of five, including his childhood friend and current police detective Bobby Dunston, stop off at a local winery. When a man walks up carrying an AR-15, which he raises, props the butt against his shoulder, and sights down the barrel - but before he can do anything, Bobby Dunston yells 'gun' and he and McKenzie take the man down. The would-be shooter was arrested, and normally, that would be the end of it. But Wisconsin is an open carry state and the police can't prove that the gunman was intended to do anything. But it does appear that he might have been looking for one specific target. And, if so, that person is not out of danger. Now, before the gunman is released, McKenzie decides to find out who was the real target and why, before it is too late.