One of ITV's flagship dramas, "Unforgotten" tackles a new interwoven story of lies, deceit, and murder each season, and brings some big names in British drama with it. Each series tackles a new case, with Nicola Walker's Cassie tasked with diving into the history of a community or group of friends who are somehow connected to a recently-discovered dead body. Season 3, which involved the discovery of a teenage girl's body on the central reservation of a motorway, was a particularly memorable, and dark, tale. Season four, the filming of which was delayed by the coronavirus pandemic, is said to be hitting screens in 2021.