The Devil You Know, Part 1 - S4.E1

When DCI Janet Chambers (Connie Hyde) goes into labor, Commander Clare Blake takes charge of the investigation into the death of a two-year-old girl found on the site of a now abandoned psychiatric institute. The girl has been dead for several years, but her body had been stored in a tightly sealed drum and is well preserved as a result. She also has a cross branded onto her chest. The pathologist's report is inconclusive, so the team start to check medical records of former patients.