When you know about the quality of the cast, the track record of the director/creator, and that the French intelligence services and former spooks contributed to the scenario, expectations run high for this series.
When you realise that it is embedded in reality and about the work of intelligence services, namely gathering and analysing information, for which the tools are brains, psychology, assets, emotions, manipulation, trading, disinformation, treachery, cyber war-fare, and other skillsets, that it's not glamorous, and that it's far less about big weapons than being able to put 2 and 2 together and making sense of constantly shifting sands and highly fluid situations, based upon which political and military decisions are made, then you know that you are onto a treat.
And, what a treat! Suspence, twists and turns, moving parts that don't always come together; all of this and plenty more are delivered, and keep you on the edge of your seat.
This is not James Bond or Jason Bourne, far from it. This is about the fastidious and ungrateful, yet highly dangerous and stressful jobs of those people evolving in the murky waters of the intelligence world. Not all saints, not all sinners, often both, and always faced with difficult decisions and their ensuing consequences, not the least guilt and sadness.
And, because intelligence officers and agents remain human after all, portraying their emotions and vulnerabilities so vividly by digging deep into their characters makes this series as real and raw as it gets.
P.S.: Watching it in its original version with subtitles in your language will take you one step closer to the action.