This is a review of Counterpart, a TV series that premiered on Starz in late 2017 and was broadcast for two seasons. It's available on Amazon Prime now. While I am not going to spoil specific plot points, I will ruin a few surprises and cover the general direction of the series. Proceed at your own risk if you haven't seen it. Better yet, go see it!
The best science fiction is about how people, society, and cultures, react to fictional science. It's not about the science. It's not about the fiction. It's about the people.
Take a look at Philip K. Dick's oft-cited definition of science fiction:
I will define science fiction, first, by saying what science fiction is not. It cannot be defined as 'a story set in the future,' [nor does it require] ultra-advanced technology. It must have a fictitious world, a society that does not in fact exist, but is predicated on our known society... that comes out of our world, the one we know: This world must be different from the given one in at least one way, and this one way must be sufficient to give rise to events that could not occur in our society…
While PKD stipulates a difference between a science fictional world and ours, he emphasizes the events the differences cause, not the differences themselves. A story about laser guns is boring. A story about people resisting a tyrannical government with a police force that wields laser guns, is (hopefully) not.
Counterpart fits Dick's definition perfectly. It's set in a world that (literally) diverged from ours in the late 1980s when a portal to another identical universe is created. (Depending on how you look at it, the event either created a portal or created the two divergent universe. YMMV.) The series is about what happens when two parallel universes suddenly have quick-and-easy access to each other.
The short and mildly spoilerly answer is that they waste no time starting up a new Cold War to replace the one the ends in the early 90s. Because of the the show plays with the timeline via flashbacks, I can't say much more without being more than mildy spoilerific. But I will say that setting the series in what used to be East Berlin, and having the portal open in the late 80's goes a long way toward setting the proper scene and mood.
Most of the characters in the series are connected to a mysterious U.N. Agency that is responsible for managing the tunnel between the universes. The departments have delight names like "Strategy," "Interface," and my personal favorite "Housekeeping."
But the Cold War between "this side" and the "other side" is part of the setting, it's neither the main driver for the plot or main source of the plot. Like any good yarn, it's the characters that drive the action.
Who are you?
What defines your identity? Your memories? Your genetics? Your environment? Your relationships? Your decisions?
What would you do if you met an alternate version of yourself? What if that counterpart had decided to take the proverbial road not taken? What if they were better for it? Or worse? Would you accept an opportunity to take over their life and enjoys the benefits or fix their mistakes?
This is good science fiction.
Of course good ideas alone doesn't make for an entertaining TV show. It needs a good script, good direction, and good acting. Counterpart has this in spades. J.K. Simmons anchors the cast play two versions of a man that couldn't be further apart. Olivia Williams, Harry Lloyd, and Nazanin Boniadi also contribute some great performances, along with an ensemble cast too numerous to name.
The writing is letter-perfect. The dialogue is natural and the pacing makes each 45-minute episode fell much longer, but in a good way. There's always a lot going on, but things never feel rushed.
Give this show a try. You won't be sorry.