When Fergal O'Brien sells a bottle of his universal remedy to the dying Leland Crawford, Leland makes a miraculous recovery, for several minutes. Then he drops dead. But before the end Leland bequeaths to Fergal his beloved Clementine, a 250-foot sidewheeler that once ruled the Big Muddy, until it sank.

Worse, Leland was in debt and now the creditors expect Fergal to pay up. With Fergal having no money, minstrel Dayton Hyde offers him a way out, but only if he kills Marshal Swift. To avoid carrying out this unwelcome task, Fergal will need to use all his cunning or like as not in this wet weather, he'll share the fate of Clementine.