With major spoilers for episode eight, here’s what we learned from the finale.
Why could Emily see again?
Emily wasn’t born blind, but lost her eyesight as part of a degenerative genetic condition. (Jonathan isn’t her biological father, which he knows but Emily doesn’t). For an as-yet unexplained reason, she and Sacha are tuned into the same wave-frequency connection shared by all the robot dogs, which enables them to feel what the others feel at the same time (similar to the connection migratory birds use to navigate in flocks) and to ‘see’. Emily’s sight is enabled when the aliens are close and she hears the ultrasound-like pulse signalling they’re nearby. It’s not like her old sight, but in black and white.
How did Catherine stop the robo-dogs?
She hacked into the low-frequency wave they use to communicate and to ‘see’, and disrupted the signal, cutting them off from alien HQ, and disabling them.
What is the connection between Emily and Sacha?
They’re both tuned into the same frequency wave as the aliens, protecting them from the invaders and letting them feel what the aliens feel. Through this connection, they both have a shared vision of each other in a loving embrace, with Emily pregnant and her circular wrist tattoo visible. When Sacha sees Jonathan’s family photo, he recognises Emily as the girl from his vision, but doesn’t tell anybody. He pretends he wants to travel to England for safety, but is really searching for Emily.
How did Sacha survive the neural blast?
Everybody who wasn’t underground, underwater or encased in metal at the time of the aliens’ neural attack died, but Sacha survived. Could it be that Sacha’s genetic make-up as the incestuous son of two siblings Chloe and Noah, separated him from the pack, so to speak? We also know that Noah was suffering from the early stages of Muscular Dystrophy, which Sacha could have inherited from him, and might affect his DNA read-out (we know the aliens were scanning human DNA). But that doesn’t explain why other genetic outliers around the world didn’t also survive.