Great cast, interesting story but it could have been a LOT better. The constant flash-backs and fast forwards, with no way of telling what part of the timeline you're in until you've been it for 5 minutes, coupled with gloomy lighting, jitterycamera work, often partially or completely concealed characters making it hard to make out who is who and, worst of all, the glacial pace of the story make this a real hard slog. You absolutely need to pay 100% attention while as the story unfolds which I don't mind but the chosen approach to delivering the story made it more difficult than it should be, so much so that they had to introduce a totally made up character in the form of Lily Thomas (new generation, anti-establishment but all laid on way too thick!) as Elliot's MI5 interviewer, just to give the audience clear signposting as to what the heck is going on. Bit of a wasted opportunity really as this story could have been told in a much more interesting and enjoyable way.