Passengers on a night ferry to New York prepare for a short, peaceful journey home, not suspecting that most of them will not reach port. Due to a mysterious anomaly, an ordinary gray mouse takes on a form that is strikingly similar to a certain cartoon star. Instead of radiating warmth and entertaining the youngest, however, it pulsates with hatred and murders the innocent. As blood floods the deck and the number of corpses threatens to sink, a group of surviving passengers must fight a bloody battle for their lives against a beast whose muzzle looks so familiar.