Counterpart

Counterpart is based on this amazing concept. Something happened during the Second World War because of which the world got split into two parallel dimensions. Now, there is an organization which keeps the balance between the world by acting as border patrol at the gateway through which you can travel to the other dimension. It all becomes visible to a low-level employee when he found out that his 'Counterpart' - i.e. himself from the other world has come through and all hell is about to break loose.

The best thing about Counterpart - J.K. Simmons. He portrayal of two different persons, who share some portion of their childhood but have a totally different life after that, is marvellous. Although, the whole cast is amazing at what they do, though many times it feels like he is carrying the whole weight on his shoulder. The show has a political angle as well, which gives the creators pretty much every liberty to work around their own imagination.