Joe, a rootless young drifter, finds work on a barge travelling between Glasgow and Edinburgh, owned by Leslie and his wife Ella. One afternoon they discover the corpse of a young woman floating in the canal. Accident? Suicide? Murder? As the police investigate and a suspect is arrested, we discover that Joe knows more than he’s letting on, and gradually we learn of Joe’s past relationship with the dead woman. Meanwhile an unspoken attraction has developed between Joe and Ella, and claustrophobic tensions evolve between the three of them in the confined space of the barge.