loureviews’s review published on Letterboxd:
Very dark for a piece of television entertainment, especially one showing at Christmas, this adaptation of the Agatha Christie book was true to her original twist, but with a nasty embellishment which proved that some people are truly evil.
Murky and gloomy, with lots of shadows and a green-blue palate, with splashes of red, with Andrea Riseborough looking especially hollow-eyed and pale as Romaine, the 'witness' of the title, and Billy Howle, by turns desperate, dangerous, and enigmatic, as Leonard Vole, the man accused.
Kim Cattrall is very good indeed as the lonely, wealthy widow Emily French who comes to a sticky end which sends her maid Janet (Monica Dolan) close to collapse after seeing the family cat lustily licking up blood on its paws. Toby Jones is the sympathetic solicitor and David Haig the cynical QC.
This has its moments but is too slowly paced and is slow to show its secrets (was there something Sapphic suggested between mistress and maid, for example?). I did like the way the ending was handled, though: far better than the shock value additions which were put in by Christie herself for the stage version, which passed over to the previous films.