Synopsis
This time the previously page refers back to Infinity #1, rather than to earlier New Avengers issues. (Avengers #18 did the same.) The Outrider brings news to Thanos from the mind of Black Bolt, that the Illuminati had possessed the Infinity Gems but lost them. Thanos also learnt that the Avengers had left Earth, so now is the time to send his 5 generals of the Black Order to take the planet.
A page at the end of the issue describes the Black Order, or the Cull Obsidian, including their powers. Some of these powers will be used this issue, so I'll summarise them here. Corvus Glaive is the top dog and most loyal. He's strong, fast, and immortal as long as his blade is unbroken. Proxima Midnight is the greatest warrior. Her spear becomes 3 deadly and unavoidable black light beams. Black Dwarf shares Thanos' love of death. He's super-strong and invulnerable. Supergiant is a mentally unstable super-telepath. Ebony Maw is the Loki of the team, who claims to have no powers.
Thanos in his spaceship is studying the data in the decapitated head of the Outrider. He sees the Infinity Gems disintegrating, but notes that one of them disappears instead. (We know from #3 that it was the Time Gem.) Thanos considers even 1 Gem is a prize worth taking, and sends his generals to interrogate the Illuminati about it. He himself will go to Earth to extract 'the tribute'.
Thanos' forces attack Earth. As we saw at then end of last issue Black Dwarf and his troops attack Wakanda, Proxima Midnight's forces reach Atlantis, Ebony Maw tackles Dr Strange by himself, and Corvus Glaive's contingent target the Westchester mutant school. We learn this issue that Supergiant is there too. A horde of spaceships appear over New York, where Iron Man and Mr Fantastic draw their fire with super-cannons in Avengers Tower. Strangely no-one approaches Black Bolt, but Attilan is hovering over New York.
Black Dwarf and Proxima Midnight are met by the effects of the Atlantis/Wakanda War last issue. The Wakandan armed forces, led by both Black Panther's T'Challa and Shuri, were already ready for a war. They repel the boarders, although T'Challa breaks a hand on BD's skin. PM finds Atlantis destroyed by Wakanda's sneak attack last issue. She offers to leave Atlantis alone if Sub-Mariner will pledge allegiance and tell her where the Infinity Gem is. To the astonishment of his ally Andromeda, Namor acquiesces but only to sneakily tell PM that the Gem is in Wakanda.
Ebony Maw has somehow bound Dr Strange and his servant Wong. He's trying to talk Strange into telling him where the Gem is. Strange, probably truthfully, denies all knowledge.
At the Jean Grey School the alien troops face Armor, Beast, Iceman, Rachel Summers, Storm and Wolverine. Supergiant takes over Iceman's mind and uses him to attack some of the others. Corvus Glaive skewers Wolverine. A combined attack by Marvel Girl and Storm makes Supergiant release Iceman. (But throughout this Thanos' guys make no attempt to target the Illuminatus Beast.)
Meanwhile Black Bolt is convinced by his brother Maximus that it's time to come clean with the rest of the Illuminati. So he triggers the signal device embedded in each of his teammates' palms.