If you like cerebral science fiction, this one's for you. Its premise is the Everett interpretation of quantum mechanics (many worlds hypothesis), in this case focusing on two parallel universes and the liminal space between them.
Masterfully written, produced and acted, it's truly a rare gem. Some didn't like the ending (questions left unanswered, perhaps more thoughtful and less action packed than hoped for), but for me, it was pure poetry. Admittedly, it really needs a season 2, so I'm keeping my fingers crossed.