The small coastal town in Suffolk, is thrown into turmoil when a teenage girl goes missing and is found murdered. Horror sweeps the inhabitants of the town, including the newly merged family of Rosie (Hermione Norris) and her two children Jamie (Alexander Arnold) and Livvy (Ellie Bamber); and her new partner Ben (Martin Clunes) and his two teenage children. Their fast approaching family holiday is overshadowed by the threat that a killer might be present in the midst of their 'safe' town. Then Rosie finds a stained pair of Jamie’s trainers hidden in his room. Concludes tomorrow.