By heck, it's a bit gory - not for those of a nervous disposition!
A tense story and quite gripping (even if we (possibly*) know the ending).
The sound quality is a bit muffled and so it helps if subtitles are on in iPlayer so -1 point for that (and some of the text is occasionally white text on a white sky background!).
(*) maybe there will be a twist in the plot, hence "probably" know the ending!