Kad astrofizičari otkriju signal iz druge galaksije, to je definitivan dokaz inteligentnog izvanzemaljskog života. Svjetska populacija u neizvjesnosti čeka daljnji kontakt. Ne moraju dugo čekati. Za nekoliko dana čovječanstvo je gotovo u potpunosti izbrisano; preostali su samo dijelići čovječanstva u jezivo opustošenom svijetu.

Nakon razornog vanzemaljskog napada, grupice preživjelih se pojavljuju u uništenom svijetu. Oni ubrzo shvaćaju da moraju staviti na stranu svoje razlike kako bi imali šansu za preživljavanje. Jer nisu sami. Nešto zloslutno vreba u sjeni i što god to bilo, neće smatrati svoju pobjedu potpunom sve dok ne ubije svakog posljednjeg čovjeka. Ali tko su ovi napadači i zašto su tako nemilosrdni u uništavanju čovječanstva?

Kako se prašina sliježe na njihovom novom svijetu, preživjeli su prisiljeni suočiti se s nekim okrutnim činjenicama. Catherine je zapanjena spoznajom svoje uloge koju je imala u napadu vanzemaljaca. Helen postaje fokusirana na osvetu. A Emily se na trenutak vrati vid. No, je li ovo čudo razlog za slavlje ili zabrinutost?

Preživjeli otkrivaju razočaravajuća otkrića ne samo o vanzemaljcima nego i o sebi. Mokrani kreće u ofenzivu ulazeći u borbu s vanzemaljcima. Ash je prisiljen donijeti najtežu odluku svog života. I Chloeina prošlost je sustiže prijeteći da će uništiti privid normalnosti koji tako očajnički pokušava stvoriti.

Počinju se pojavljivati trzavice dok se preživjeli pokušavaju nositi s novim načinom života. Jonathana sve više uznemirava Sachino čudno ponašanje. Emily postaje zanimljiva zagonetka Billu. A Mokrani je užasnut dok njegovi ljudi uživaju u mogućnosti osvete.

Veze izvanzemaljaca s nekim preživjelima nameću brojna pitanja. Bill otkriva iznenađujuće otkriće. Sachino ponašanje postaje sve nepredvidljivije. A Tomov rođendan je prilika za malo slavlje. Ali pod koju cijenu?

Katarinini prioriteti mijenjaju se dolaskom Sofije. Odnosi Jonathana i Sache eskaliraju. A Emily je toliko sretna što opet vidi da je prestala pitati zašto iako drugi nisu.

Preživjeli pokušavaju preokrenuti tijek borbe s napadačima jednom zauvijek. Mokrani i Katarina pripremaju se za borbu svog života. Emily traži odgovore pod svaku cijenu. I Sachine vizije se nastavljaju i pružaju zbunjujući uvid u budućnost.

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.

Bill joins the military group formed by Ethan, Dominic and Michael. The three men hold a young alien hostage, Isla. Catherine, Sophia and Nathan continue to search for Bill. Adina, and the aliens also set out to find Bill. Chloe accuses the blow when she realizes that Sacha killed Ash. She suggests to her increasingly unstable son to run away with her.

At the university, Sophia watches the videos recorded by Dylan, a young man they found dead, while Catherine focuses on the algorithms he left behind and which decipher the behavior of robots. Thanks to Bill's intervention, Isla manages to flee and join her family.

Emily agrees to help Bill test her for the virus, but soon experiences serious side effects. Sacha, who has secretly followed the group to stay close to Emily, tries to remove her from the group. For their part, Catherine, Sophia and Nathan set out again in search of Bill Ward.

Catherine, Sophia, Zoe and the other survivors, finally reunited, prepare for the ultimate attack. But it is Bill who is the only one to hold the fate of humanity in his hands, provided he is helped by Isla.

After saving humanity, Bill Ward finds himself locked up in prison. Bitter, he will take a close interest in a new subject: many people around the world are victims of mysterious visions, including MI5 agent Zoe. Meanwhile, the discovery of a black hole prompts Catherine to investigate this global phenomenon.

Astronauts Juliet Arquette and Richard Gallagher witness Catherine's theories in space as Adina plots revenge against humanity. Mourning over the death of her sister, Catherine decides to research the phenomenon with the help of Johannes. An unexpected encounter prompts Kariem to continue her investigation of global psychosis. Faced with the damage caused by Adina's latest attacks, Zoe decides to turn to Bill to thwart the alien's plans.

Richard discovers new data on the global phenomenon. Catherine must take a risk to continue her research, but is she ready to do it? Meanwhile, a new revelation tests Martha's loyalty, and Zoe is forced to make an urgent sacrifice with the help of her newfound allies.

Betrayed, Tom forges an unexpected alliance with Zoe. Confronted with the teenager, Bill must again answer for the consequences of his sacrifice. Zoe takes a drastic step to stop Adina's plan. From the alternate world, Catherine discovers that interstellar activity is badly affecting people. She sets out to find a solution, but is in serious danger.

Martha unwittingly unleashes a fatal gunfight resulting in severe damage. In the alternate world, Catherine and Sam arrive at their destination, but encounter some unforeseen events. Bill then tries to contact Catherine, but when he can't reach her, he turns to a drastic solution.

Bill investigates more of Catherine's findings and thwarts the aliens' deadly plans, but the group finds themselves in danger once again. Meanwhile, a run-in with the aliens ends tragically. Catherine secretly hatches a plan against her captors, but will she abandon Sam?

Catherine shares vital information about the black hole with Richard. Martha discovers Adina's destructive plan which the resistance group confronts. With little time left, the group is forced to take ever greater risks and make painful sacrifices to save the world.

Helpless against Adina's plan, Bill has no choice but to make a risky bet while his comrades prepare for a brutal end. In space, Richard and Juliet realize how close humanity is to annihilation, but will they be able to go to any lengths to save Earth?