Creegan and Taylor come closer to identifying the killer when a fourth victim, headteacher Claire Logan, is found dead. They soon realise that victim Debbie Lewis' best friend, Lyn Sotherby, is none other than Susan Etchells in disguise, and they soon track her down to a disused hospital in Lincolnshire, where she has another victim ready and waiting. Creegan then puts himself on the line to secure the safety of the hostage, much to Taylor's dismay.