The fourth season opens with the discovery of a dismembered body in a scrap metal yard, which the team believe has been stored in a domestic freezer for thirty years. A unique Millwall Football Club tattoo leads to the victim being identified as Matthew Walsh, a young man in his mid-twenties who went missing in March 1990.

• Sanjeev Bhaskar
• Sinéad Keenan
• Carolina Main
• Jordan Long
• Pippa Nixon
• Georgia Mackenzie
• Ian McElhinney
• Hayley Mills