While the Avengers are in space opposing a massive alien threat, Thanos and the Black Order launch an attack against the Earth. The Avengers journey to deep space to unite the Kree, the Shi'ar, the Skrulls, and countless other intergalactic races against the Builders—technologically advanced aliens with an armada large enough to destroy the known galaxy. While the heroes are absent, Thanos the Mad Titan sets his sights on Earth, sending the Black Order to launch the assault. It falls to the other heroes of Earth—the Inhumans, the Black Panther, Namor the Sub-Mariner, Doctor Strange, the X-Men, and more—to defend Attilan, Wakanda, Atlantis, and the rest of the planet. To defeat Thanos, the defending forces will need to employ a new weapon—one that may be as deadly as the invading force.