This time the action moves from the rails to the open water, as a new high-stakes thriller unfolds aboard a ship travelling across the Irish Sea - and behind every cabin door is another story, another surprise... The passengers and crew on tonight's Belfast to Liverpool passenger ferry are about to experience six hours of non-stop thrills and spills, secrets and lies, triumphs and tragedies. None of them are quite as they seem. Nothing in their lives will ever be the same again. Not all of them will make it to the other side.