I love a good spy thriller, but sadly this doesn't seem to be one of those. It starts with that mega annoying device of showing the audience something dramatic just about to happen and then dragging them back to a week - or a month - earlier to explain how they got there.
So we start with the climax and then we're dragged back to a middle-aged guy going for a drink to a mega posh bar where apparently there's no security, because anybody can enter from the back door and pretend to be a waiter, just by stealing a conveniently left around apron.
This scene has been done a million times and somebody should do something about security in bars and restaurants, because a million villains use them to enter premises undetected.
Moreover, if you think about it, it is extremely difficult to pull off an attempted assassination by serving a drink you did not hear being ordered and managing to do so before the legitimate waitress. Also, nobody questioning a perfectly unknown waitress walking around a posh bar is extremely unlikely.
From this scene, everything goes downhill, with Charlie Cox, a very young guy, being the head of MI6 and throwing secret services in a shamble. It does not help that the main cast is actually a bunch of female actors, from the wifey - who's the real protagonist, to the head of the CIA task force (another almost underage female), to the "villain" Kara, ending with the inevitable, cliché spoiled teenage daughter, who's the plague of most TV series.