Joe is a drifter who works as a hired hand on a barge traveling the Clyde River between Glasgow and Edinburgh. As the story opens, he finds the corpse of a young woman drifting downstream. Was it an accident? Suicide? Murder? As the police investigate and arrest a suspect, it becomes apparent that Joe knew the dead woman and has more information than he's telling. Meanwhile, an unspoken attraction has developed between Joe and the wife of the barge...