Synopsis
The Avengers team and the Guardians of the Galaxy are facing a cosmic-sized Thanos who's merged with a Cosmic Cube.
Thor leaves the Guardians' ship to attack Thanos, while Iron Man transmits an update to Mr Fantastic and the rest of the Avengers back on Earth. Tony Stark reminds the others that it isn't a real Cosmic Cube. It's an approximation built on Earth, and he has the blueprints. Therein lies their hope.
But Thanos's Cube seems to disintegrate Thor, and then the Guardian's ship.
For the purposes of suspense we shift to a scene of Reed Richards (and Thing) telling the President what's going on. The transmission from Stark terminated abruptly, and the Earth had better prepare for an extinction-level event.
We turn the page and find that the Avengers aren't dead yet. Their ship is in what Star-Lord recognises as the Cancerverse. But he can't or won't tell them how he previously escaped from here.
Tony says that this 'Cosmic Cube' is actually a dark matter portal siphoning massive amounts energy from the Cancerverse. Thanos thought it was a real Cube, but it's not working as he expected. Stark figures he can tell from the plans how to block the flow.
It turns out that the Elders of the Universe Thanos 'killed' last issue have also really been banished to the Cancerverse. The fake Cube couldn't actually kill them. Stark explains to them about the fakeness of the Cube, and asks for their help with his plan. Collector offers the use of anything in his collection.
The giant Thanos has reached Earth, and the Fantastic Four and lots of Avengers are preparing to do battle. Mr Fantastic is even threatening to use the Ultimate Nullifier. But just then the Guardians' ship pops back into this universe. Iron Man and Thor are flying ahead, and Thor's got a very big gun. 1 zap and Thanos is separated from the Cube and back to normal size.
Hulk climbs out of the ship and throws Groot at Thanos. Groot grows into an enormous tree-thing and smashes Thanos to the ground. Where loads of heroes pound on him. The villain is battered but unbowed. But then the Elders appear and take him away.
In an epilogue Captain America wants to know why the army was building a 'Cosmic Cube' without telling the Avengers (or more specifically him, in his post-Dark Reign role overseeing all defence). Maria Hill says it was a back-up in case the Avengers failed, or went rogue.
The Guardians head back into space. Tony Stark wishes he could go with them, and Peter Quill extends an invitation.
In another epilogue the Badoon swear to rule or destroy the Earth in revenge for the loss of the warship and all hands in #6.