There is another you out there.
Why it is hard sci-fi
A two-season series about a covert agency that polices the boundary between two parallel Earths that diverged at a single laboratory experiment in 1987. The show commits to a single working idea. The agency runs a single crossing point under Berlin and tracks every agent who passes between sides. The procedural texture is Cold-War spycraft applied to two civilisations that share a common past. The show is one of the few portrayals of a multi-decade divergence between two real societies.
Science inside it
A localised cross-universe aperture with a working single crossing point, a divergence accumulated over thirty years across two societies, a working blue-flu epidemic in one of the universes that explains its different political pathway, and a procedural shape of agents who have a counterpart in the other universe and have to negotiate the relationship.