Cracks start to show as the survivors find different ways to cope. Jonathan’s increasingly perturbed by Sacha’s strange behaviour. Emily proves to be an exciting conundrum for Bill. And Mokrani is horrified as his men delight in the opportunity to exact revenge.

The alien’s connection to certain survivors raises difficult questions. Bill makes a startling discovery. Sacha’s behaviour is increasingly erratic. And Tom’s birthday proves cause for celebration. But at what cost?

Tragedy strikes, altering the course of the future forever. Catherine’s priorities change with the arrival of Sophia. Things come to a head between Jonathan and Sacha. And Emily’s so happy she can see again that she’s stopped asking why, even if others haven’t.

The survivors attempt to turn the tables on their aggressors once and for all. Mokrani and Catherine prepare for the fight of their lives. Emily seeks answers, at any cost. And Sacha’s visions continue, giving a confounding glimpse of the future.

Six months after Emily disappeared on an alien ship, the London survivors have set up a resistance base from which they plan to fight back; the aliens have since appeared and they look exactly like humans.

As Emily grows concerned by her recollections of time spent with the aliens, Bill is also perturbed by the similarities between Emily and the aliens; Zoe encourages a reluctant Bill to use these similarities to their advantage.

Bill secretly injects Emily with a biological weapon he hopes to use on the aliens; when she becomes sick, some of the survivors head out to find insulin in order to treat her; the resistance base is attacked and the survivors are forced to flee.

Catherine, Sophia and Nathan make their way to London, accompanied by Victor, a survivor encountered by chance. Along the way, the dangers multiply. Sacha's feelings towards Emily intensify and the young man's behavior becomes more and more disturbing. Feeling threatened, Bill is forced to flee.