Walker plays Cassie Stuart, a middle-aged detective chief inspector (DCI) whose unit is responsible for investigating cold cases using new techniques such as DNA matching. She is assisted by her partner, Detective Inspector Sunny Khan (played by Sanjeev Bhaskar), who seemed catatonic in the first two dramas in the series, but has evolved into an emotionally engaging character in the third. Unlike other police dramas, the quality that stands out in these two characters and indeed their entire investigative team (thanks to writer Chris Lang) is compassion, a quality that while ennobling their quest for justice, takes its toll on their already fraught personal lives.
We’ve seen Walker before as the farmer in Last Tango in Halifax (another spoiler) who lets her abusive husband die only later to fall in love with and marry his brother. She has ice-blue eyes and a haunted, craggy beauty with lines that seem cruelly etched into her face. At the same time she can convey vulnerability and the steely toughness of a survivor. I don’t know whether this face-focused approach to acting would work on the stage, probably not; but with Walker’s film portrayal of someone at the top of their game falling apart professionally and personally, it is acting at its best.
