Fantastic Four/Inhumans: Atlantis Rising written by Glen Herdling, Tom Defalco, Tom Brevoort, Mike Kanterovich, and Roy Thomas with Paul Ryan; art by Geof Isherwood, M.C. Wyman, Paul Ryan, and others
Morgan le Fey, evil witch of Arthurian legend, decides to raise havoc by raising Atlantis from the Atlantic floor. She wants to claim it as her ancestral home, Avalon, that sank beneath the sea millennia ago. The Inhumans, a hidden race that has moved from hiding place to hiding place (currently on the far side of the moon), also claim the land as their lost homeland. A freak accident by Nathaniel Richards (Reed Richards's father) has jeopardized the Inhumans's lunar home, so they need another place. Prince Namor, the Sub-Mariner and exiled king of Atlantis, naturally wants the land back under the sea and claims it for his people. The Fantastic Four (minus Reed, who died along with Doctor Doom battling aliens before this story started) has recruited Scott Lang, the second Ant-Man, to work with the team (and presumably keep the "Four" in "Fantastic Four"). They rush to the aid of the lunar Inhumans and then get involved in the Atlantis shenanigans.
The plot is rather complicated, which is a strength since it generates plenty of conflict and excitement. Even with a huge number of characters (I didn't even mention the Fantastic Force, a spin-off team from the Four), readers can follow what's going on and don't get lost in the chaos (something that happens in the Age of Apocalypse graphic novels). For a big crossover event, it's a fun and satisfying read.