After helping Jacques Schnee defeat Robyn Hill in the election for a seat on the Atlas Council through hacking. Arthur Watts used the backdoor access into the mainframe to shut off Mantle's heating grid. The resulting panic spirals into a riot as people set fires for warmth and attack military personnel. Multiple Grimm are drawn to the negativity penetrating a gap in the defensive wall. Overwhelming efforts to keep them at bay.
Team RWBY, Team JNPR, the Ace Operatives and Qrow Branwen mobilize to assist the defense. En-route their Manta is attacked by a pair of Teryx and badly damaged. All of the Huntsmen successfully bail out landing in Mantle.
Atlas soldiers gun down Beowolves on the streets while civilians flee. Airships chase flying Grimm while providing supporting fire. The Happy Huntresses and Nora Valkyrie kill multiple Sabyrs to protect civilians. Blake Belladonna leads a Megoliath and two Ursai down a street, using her Semblance to avoid them. The Megoliath eventually tramples one Ursa before Elm Ederne stops it, Yang Xiao Long slides under the Grimm and plants several explosives. At her signal, Elm heaves the Grimm into the air just before Yang detonates them. Once the area is clear they direct civilians to head for shelter then prepare for the next clash.
Qrow Branwen stands on a rooftop firing at passing Grimm, as Clover Ebi receives new instructions via earpiece. Back at street level, Marrow Amin battles more Grimm joined by Weiss Schnee and her Arma Gigas summon. As the situation worsens despite Nora's efforts to calm things people begin accusing Atlas of being responsible. Then a screen comes on showing Robyn Hill using her semblance on James Ironwood, as he reveals the existence of Salem. Proceeding to state her agents Arthur Watts and Tyrian Callows are behind the string of murders and heating failure. Explaining the supplies he diverted from Mantle were for the Amity Communications Tower before claiming it is completed. Declaring the units defending it will be diverted to help protect and evacuate Mantle.
As this occurs Ruby Rose, Harriet Bree, Jaune Arc, Lie Ren and Vine Zeki continue protecting the people of Mantle. Vine pins multiple Grimm against walls as Jaune directs people down the street, while boosting Ren's semblance to mask their fear. Numerous ships begin landing as civilians board while Elm defends one from Megoliaths with her rockets. Penny Polendina joins the fight as Ruby struggles to activate her Silver Eyes, unable to focus long enough she instead provides support from a roof. Penny attacks the Megoliath with Floating Array , but it is unfazed and tosses her away. Harriet narrowly escapes being crushed, sustaining heavy damage to her Aura. Following Ruby's suggestion Penny severs one of its tusks and they work together to impale it.
As this goes on Watts makes plans to sabotage Amity, while Tyrian hunts down Robyn Hill. Cornering her in an alley only to be confronted by Qrow and Clover revealing Ironwood set a trap, readying for a fight which leads to his arrest. As Watts arrives on Amity coming face to face with the General himself.
Following Watts' arrest after his battle with Ironwood, James enters his office, finding that Cinder Fall has infiltrated the Academy in the panic, causing him to recall RWBY, JNPR, and the Ace Ops back to Atlas, abandoning Mantle.