Sergeant Dan Scott (John Hopkins) arrives to work with Barnaby and is thrown straight into a murder investigation in Midsomer Mallow. A squeaking noise heard near the scene of Fiona Thompson's bloodstained body leads police to suspect an odd job man. But when the murder toll rises, Barnaby becomes concerned for Cully, who is organizing a 10-year reunion with her old school friends. Guest stars include Ruth Jones (Gavin & Stacey).