A mission to procure vehicles and fuel goes awry. Cochise shares troubling news with Anne that will test both her medical and leadership skills. Anthony’s mental stability and his loyalties are brought into question. Meanwhile, a desperate Pope takes things into his own hands.
The fractured Hawkins family reaches its lowest ebb, with dad Joe in exile, and Mattie, Toby and Sophie tired of their parents’ lies. As the situation reaches breaking point, Laura decides it is time to tell the truth, and her confessions has incredible consequences for household synth Anita. Meanwhile, Karen finally discovers `killer synth’ Niska’s whereabouts, and a joyful reunion for the runaways is cut tragically short when a brutal betrayal forces one of their number to make the ultimate sacrifice.
Harvey steps outside his usual area of expertise, in order to take a case from a client who has a special tie to the firm. Mike and Zane work their class-action case together, but Mike learns they have different ideas about what constitutes a win – for themselves, and for their clients. And Donna counsels Louis on the best way to settle a feud.
The 2nd Mass discovers the source for the seemingly endless supply of enemy forces. With the Volm’s help, Tom’s leadership begins to spread to remaining human militias around the world. Hal disobeys his father to help Maggie on a personal mission. Meanwhile, Tom has to make an agonizing choice that ultimately risks one of their own, leaving lasting repercussions for them all.
News of the `Killer Synth’ finds its way into the media, causing widespread panic, and placing Karen under even more pressure to track down the alluring fugitive Niska. However, it seems there may be an ulterior motive to her hunt for the murderous synth. Meanwhile, the Hawkins debate whether to keep Anita in light of their recent discovery that she is not quite as `new’ as she seemed, and while Joe worries his domestic synth might inadvertently reveal his secret, Mattie’s decision to place her trust in Leo could put an end to the family’s arguments.
Harvey brings some star power to his ongoing conflict with Jack Soloff – a conflict that Louis and Donna can’t seem to stay clear of. Mike brings in Robert Zane to co-counsel a case, pitting his instincts as a lawyer against his desire to stay in his future father-in-law’s good graces. And while Jessica mediates between Mike and Zane, she tasks Rachel with an unusual assignment.
A surprise skitter attack leaves the 2nd Mass without food. In desperation, Maggie, Ben, Pope, and Sara go on a dangerous mission hoping to find supplies.
Laura feels vindicated when Mattie tells her that she has seen Anita acting strangely. Laura insists that the family take Anita for testing and they’re shocked to discover she’s 14 years old. After meeting Leo through the Headcracker forum, Mattie thinks she might have an idea. Pete becomes stir crazy, stuck in the house with Simon.
Harvey searches for a replacement for Donna. Mike takes a case as a favor, which he must justify to Jessica – while Rachel’s father, Robert Zane, offers some unsolicited advice about Rachel’s engagement to Mike. And Louis is embroiled in surprising money matters, while an up-and-coming partner, Jack, makes his presence known to Jessica, confronting her about whether Harvey’s way of doing business is beneficial to the firm.
On the heels of Tom and Lexi’s successful albeit tragic mission to destroy the Espheni power core on the moon, we pick up with Tom’s life hanging in the balance as his Beamer drifts into space. While onboard the beamer, Tom encounters a surprising guest who urges him to find his inner warrior. Meanwhile, back on earth, Anne reluctantly steps into Tom’s shoes to help lead the 2nd Mass in his absence. Against all odds, Tom makes a miraculous, yet mysterious return to earth. Once reunited with the 2nd Mass, Tom shares a new plan for winning the war. The Espheni, for the first time, are on their heels, and the 2nd Mass will not rest until they are gone from this planet for good.