At the dawn of the civil war, the steamboat "Arabia" pushes up the Missouri river and strikes a submerged tree trunk and sinks. 131 years later in 1987, Bob Hawley, patriarch of a family of treasure hunters, entices his sons Greg and David with the lure of gold and silver rumored to be aboard the boat. Greg is reluctant having promised his wife, Karen, to put such frivolity behind him. For David the project is a useful distraction from his troubled marriage to Laurie.

The brothers locate the steamboat and with a cobbled team of volunteers and bartered equipment, begin the dangerous excavation. Word of the project reaches "Missouri" Anderson, an unscrupulous archeologist who then deploys attractive pre-law student Delia to infiltrate the dig.

Despite cave-ins and sub-zero weather, Greg and David reach the decks of the Arabia. David rummages through cargo for treasure, while Greg believes they may have already found it -- a one-of-a-kind portrait of mid-1800's pioneer life though 200 tons of furniture, glassware, tools and leather goods, all perfectly preserved.

But not for long. Exposed to light and air, the artifacts face immediate deterioration. Greg throws himself into preservation of the artifacts. To defray skyrocketing costs, David proposes selling artifacts, but Greg is adamant about keeping the collection together.

The hard work underway, the archeologist files an injunction to wrest the find from the amateurs. David's obsession with the Arabia is the last straw for Laurie who files papers of her own, for divorce. Greg approaches museums with the collection in exchange for funds to complete the dig, however the museums decline.

Greg and David are clearing the steamboat's bow when their discord erupts in a violent argument, only broken as a tidal wave in the bow swamps them. They escape but not before David reveals that a quorum of investors have committed to an auction to pay off debt.

Later, Greg is transporting a final load of artifacts when he is killed in a freak traffic accident. After the funeral, Greg's widow Karen acquiesces to David's auction. But before it can take place, David stumbles upon a series of clues that his late brother had a viable plan to keep the Arabia collection intact..

Thanks to a "friend of the court" brief filed by Delia, the court reverses the archeologist's injunction, paving the way for what Greg had envisioned before he died: a for-profit enterprise, "The Treasures Of The Steamboat Arabia" Museum. While it will never make them rich, David and the Hawley family are reconciled in a new mission: as permanent caretakers for the largest collection of pre-civil war artifacts ever assembled anywhere in the world.