Captain Culpepper"s 235-foot-long sternwheeler, the steamer Barnard Clinton, is going to try to make a record second trip in 1866 to the head of navigation on the Missouri River. The railroads are expanding, and the successful trip of the big steamboat has attracted the attention of some unscrupulous railroad investors. They would like the big steamer to fail, and to this end, they have hired several bad characters to join the steamer on her upriver voyage. They intend to sabotage the vessel, and if there is loss of life, so much the better. Culpepper and his crew will have to deal with these outlaws, low water, other outlaws, Native Americans, and a young pilot who can"t seem to keep the Clinton off the bottom of the river. And, as if he didn"t have enough on his mind, the captain is distracted by a beautiful but mysterious lady.