Cassie and Sunny identify four potential suspects who trained as police probationers together, and two of them are still serving officers. They have no luck finding the rest of the body and decide to go public about the discovery of Walsh's remains.

Unforgotten Season 4 Episodes...

• s04e01 - Series 4, Episode 1
• s04e02 - Series 4, Episode 2
• s04e03 - Series 4, Episode 3
• s04e04 - Series 4, Episode 4
• s04e05 - Series 4, Episode 5
• s04e06 - Series 4, Episode 6

Unforgotten Show Summary

Nicola Walker and Sanjeev Bhaskar star as detectives investigating a 'cold' cuddle case of 39 years ago.
When the bones of a young man are found beneath the footings of a demolished house, an investigation begins that will unravel the lives of four people who have been waiting for this moment for nearly forty years, as they discover that the past can't, and won't, stay buried forever.