18-year-old Emmett Watson has just been released early from Salina, a juvenile detention center. His father's death has granted him early release, but also spelled the loss of their family farm and burdened him with the sole responsibility of caring for his younger brother Billy. Emmett, who is ready to begin a new life for himself and his brother with steady work as a carpenter, has made plans to move West. Billy proposes San Francisco as a destination, as he wants to trace the route their mother once followed when she left them eight years ago—along the Lincoln Highway.
Emmett’s carefully thought-out plan is rapidly derailed when Duchess and Woolly show up. They have recently escaped from Salina, and share a plan to reclaim Woolly’s rightful inheritance, which is considerable. Emmett refuses, but agrees to give them a ride to the nearest city. But he and Billy are sucked into Duchess and Woolly’s path to New York when the latter two drive off with Emmett’s car.
As Billy and Emmett hop a train going in the opposite direction of California, Duchess and Woolly make stops along the way to the house of Woolly’s great-grandfather in the Adirondacks. Duchess, resolved to “settle his debts” before a fresh start, detours at the house of an ex-warden at Salina before moving to track down his father. Billy has a run-in with an avaricious pastor, but is narrowly saved by the interference of a WWII veteran named Ulysses. When the four boys’ paths converge in New York, Woolly visits his sister’s house and Duchess draws closer to his father, who has gone missing in the days since Duchess’s escape from Salina. With the help of various strangers and Townhouse, a former inmate of Salina, Emmett manages to trace Duchess’s steps, eventually finding him at the circus. Their long-awaited confrontation goes peacefully at first, until Woolly's tragic overdose death. With Woolly’s remaining inheritance up for grabs, Duchess’s greed threatens Billy and Emmett’s lives. Thanks to Billy’s keen attention to detail, he and his brother are able to prevail, and Duchess is left to drown to death when he gives in to his greed once more.
