Synopsis
The previously page shows Maximus building something for Black Bolt, while Black Panther and Mr Fantastic constructed anti-matter bombs to destroy alternate Earths. Meanwhile Sub-Mariner asked T'Challa to intercede with his sister Shuri to stop her taking Wakanda into war with Atlantis. But Shuri decided on war.
It's now 1 week later. Tony Stark has returned from his adventures in space with the Guardians of the Galaxy, but Reed Richards is still commuting from his family's holiday in space-time. Reed asks about Tony's trip, but Tony says there's no time for that. (But he remembers standing with a Watcher next to the body of the Living Tribunal.)
As Tony dons his space Iron Man armour he says that the Avengers have just left Earth to deal with a galactic threat, but he stayed behind to organise Earth's defences. But Stark also believes that there is a bigger threat that they 2 must handle - the very universe is crumbling. They cryptically decide to 'eliminate a variable'.
In the Inhumans' flying city Attilan, currently hovering over New York, Maximus has created 2 devices for his brother the king. The 1st is something to do with the Terrigen Crystals. The 2nd is a portal to a dimension where Black Bolt can speak without the destructive effects of his voice. Now the Illuminati can hold meetings and Black Bolt can join in freely. (Maximus reveals that he knows about the Illuminati because he put a tracker on the teleporting dog Lockjaw.)
But when they return home it is to face an angry Medusa. She enters telepathic communication with her husband and demands to know what he's been hiding from her. (He's been keeping secret what Maximus has built for him. He also didn't tell her about the Illuminati, but she found out in Avengers (2010) #8) Now he (cryptically to us) lets her know what he intends to do with the Terrigen Crystals, with it seems dire consequences for the Inhumans.
Sub-Mariner visits the captive Black Swan in the Wakandan Necropolis. He offers a partnership to (I think) take a more drastic approach to the incursions. But they are interrupted by Panther.
Namor thinks the Wakandans accepted his peace proposal. But T'Challa says Shuri turned it down, But they haven't told the Atlanteans. Now while Sub-Mariner is here, the Wakandans have attacked Atlantis. Namor flies off to help his people.
Iron Man and Mr Fantastic return to Avengers Tower from hiring some unspecified person, presumably to 'eliminate the variable' they spoke of earlier. Just in time to see invading spaceships in the skies over New York. Dr Strange sees an alien (Ebony Maw) approaching his Sanctum. Other aliens and their fleets attack Wakanda (where both Black Panthers [T'Challa and Shuri] join forces against Black Dwarf), the Jean Grey School (Corvus Glaive faces Armor, Beast and Wolverine), and Atlantis (Proxima Midnight finds Namor amidst his fallen people).