In April, 1862, the Civil War is just starting its second year of fighting. Riverboat owner and captain Bill Horn wanted to fight for the Union, but it was decided he could better serve his country by using the Western Star to ferry troops and supplies. Kay Graham, owner and pilot of the Queen, had been his biggest competitor for business on the river, but she too is now using her boat and skills for the Union. Jack Wade had always been a rival of Bill's. Bill assumed the hostility was rooted in jealousy since Bill was the son of a prosperous steamboat owner and Jack was the son of a poor sawmill worker. Wade had been responsible for wrecking one of Horn's steamships, then he'd stolen Horn's fiancée. When the Civil War started, Jack had gone to fight for the South, but he soon realized the South would never win and became the leader of a group of Jayhawkers. They try to cause as much trouble as they can for the Union while making a profit for themselves. When Horn and Graham are asked to take troops and supplies up the Missouri to Fort Union, where the 5th Cavalry will be launching a campaign against Chief Wild Horse and his Sioux, their paths will once again cross with Wade and his Jayhawkers in a struggle to survive.