Simply put - nothing is believable, unless you are a very simple person and you desperately wish that the world would work the way it's presented in this series.
These people work in the field of security? Believe it or not. Spies? Sure. Tsunami? What? 15 years, sure?
Who wrote this? Who directed this? We know who acted in this, and that's a shame. Yeah, it was the Viking dude camouflaged with a baseball cap that didn't fit his head, and then a bunch of various amateurs.
Despite of all this I managed to watch this till the end. This is because I've watched everything else. Already during the first episode, I had to switch to the moron mode so that I'd get through it, but this disaster continued with even worse plot twists one after other and it looked like it every episode was written a day before they shot it, but hey what can you do if you don't have anything else to do.
Clive Standen, I'm going to forgive you this time and hope you're going to make it. That's purely because of your high level of coolness in the Vikings. Like in the X-files, I want to believe.