Infinity and, presumably, the upcoming Secret Wars).
It's the first of the post-Infinity collections. That story, a line-wide crossover series by Hickman, still seems like more of an interruption to Hickman's Avengers/New Avengers storyline than a key part of it, although it did move minor plot points and characters around. The events of Infinity are rather explicitly referenced in a conversation about the massive Avengers roster that Captain America and Iron Man engage in during the first of these stories, when Stark tells Cap that "The Avengers helped win an intergalactic war," but warns him their "Avengers Machine" (just a spiral-shaped diagram, really) needs to be flexible and able to grow, to deal with perhaps even bigger threats (the conversation also serves the purpose of explaining why we won't be seeing anymore of Spider-Man and Wolverine in these pages for a while, as they have events in their own books to attend to).
Later, when Bruce Banner confronts Stark about what he's been up to in the two books, Banner points out the big, huge, powerful Avengers roster is actually a pretty good clue that Stark is up to something: "You needed a team so powerful that it could handle any overt threat while you worked on the real problem."
But let's not get ahead of ourselves.
The first of the three stories collected here—all apparently drawn by Salvador Larroca and colored by Frank Martin, although three other artists helped out on #24—includes one of my favorite sorts of superhero team scenes, the "everyone just kinda hanging out and doing normal stuff" scene. Sometimes whole issues of superhero comics will consist of a half-dozen of such scenes, generally as opportunities for breath-catching, line-up tweaking and status quo restating between big, dramatic multi-issue arcs.
That's not quite the case here, although some of that does happen. It begins in the year 3030, with Franklin Richards sending a Iron Man back in time to warn the Avengers of something pretty horrible about to happen to them, something only a team as big and full of geniuses and god-like super-beings as this particular Avengers like-up could deal with effectively. Prior to the warning, The Avengers are all just hanging out on Avengers Tower's penthouse, Starbrand and Hawkeye trying to shoot golf balls out of the sky, while Thor works the grill without a shirt on.
Maybe I'm easy, but I really enjoy Thor talking about foodstuffs in his Shakespearean sentence structure, personal font and superhero-like sense of urgency:
a runaway planet or, worse, a rogue planet that someone or something apparently fired like a bullet at Earth millions, maybe billions of years ago. And it's up to The Avengers to stop it. Rather than just pushing it out of the way, as DC's Justice League would do, or maybe obliterating it before it gets too close, they have an even weirder, more unique solution to the problem. That's one admirable aspect of Hickman's run: While so much of it is predictable superhero business, Hickman twists its nature and the nature of the solution from the predictable, standard superhero solutions into something different.
This is basically just Superman punching away asteroids or catching a plane, but Hickman turns it into an event requiring time-travel, a dozen super-powered beings, a workshop on Mars, Superman-like strength and magic god hammer and an act o of super-science....while also using it as another clue that Stark is up to something beyond what his teammates in this particular book may think.
Which takes us to the next storyline, where another generic superhero trope occurs: Evil versions of the title characters from an alternate dimension (Stark actually seems somewhat embarrassed when explaining the conflict later).
Hickman's twist? Well, interestingly enough, these Avengers look identical to the original Avengers from the 1960s, with no spikes, chains or black goatees to reveal that they are actually bad guys until Thorr (there's an extra "r" in his universe, apparently), kills a bunch of civilians.
More importantly, it ties into the mega-story driving the two books. These Avengers are plucked from an Earth that has just been destroyed during an "incursion," and their presence on Marvel's Earth, however briefly, provides one more clue to what Stark is up to, as well as the means for this Avengers team's other super-genius to put it all together.
The final story in the volume, is a fairly simple one, but probably the most dramatic of the book...maybe the run so far. Bruce Banner walks into Avengers Tower with a brief case, sits across a table from Tony Stark, and starts laying out the case against Stark he's put together in his head. He knows Stark is up to something, he knows Stark is building incredible, world-destroying weapons and he knows he's apparently working with Reed Richards and others in a re-formed Illuminati (That's a pretty sore subject with Banner, as it was The Illuminati wo, some years ago, decided to capture him and shoot him into space as the most sensible way of dealing with the Hulk problem, which Brian Michael Bendis and the Marvel of the time retconned into a very dire problem, as now Hulk's rampages resulted in civilian deaths all the time instead of, you know, never ever resulting in any civilian deaths. This, of course, lead to the popular "Planet Hulk" storyline and then the pretty damn awesome World War Hulk event series, one of the better of the post-House of M Marvel event series).
He grills Stark, while Stark can't stop asking what is in the brief case. It's a pretty dramatic reveal, adding yet another layer to what is already a dramatic moment, regardless of how well one knows the characters (Like, even you weren't reading Bendis' Illuminati comics, or the Greg Pak and company run on Hulk comics, there's plenty of reason for Bruce Banner to be appalled and furious at Stark and his cabal for 1) Keeping the possible imminent destruction of all reality from the rest of the world and 2) Preparing to do the unthinkable and kill billions of people in order to save trillions and trillions of others. Hickman has essentially created the ultimate moral dilemma here, taking the standard superhero dilemma of whether or not to kill a villain even if one's own moral code forbids the taking of a life, in order to save all of that villain's future victims, but multiplying it so astronomically it's no longer even possible to think of a bigger version of the dilemma (Here further magnified by the fact that it's not a villain being discussed, but an innocent planet).
Thus confronted, Stark has one of two options: Take Banner down, or invite him in. And Banner, of course, has two equally unappealing choices: Join Stark in The Illuminati, or take him down...and assume the burden of saving The Multiverse without the benefit of Stark, Reed Richards and the others.
It's pretty powerful stuff as superhero morality plays go, although I suppose it's worth noting that this particular plotline is continued not in the next volume of Avengers—although that story arc is premised on Captain America remembering The Illuminati, the incursions and the unthinkable moral dilemmas—but New Avengers.