Passing through New Orleans, Lucky Luke stumbles upon a heated argument between two steamboat captains. The argument soon turns into a wager: whichever boat reaches Minneapolis first after steaming up the Mississippi will win the exclusive rights to the route. Captain Barstow quickly invites Luke to travel on his Daisy Belle, fearing that his opponent will cheat. And while he's not wrong, the biggest danger to both boats remains Old Man River himself...
