WARNING: The following contains spoilers for What If...? Season 1, Episode 3, "What If... The World Lost Its Mightiest Heroes," streaming now on Disney+.
After showing what the universe would be like if T'Challa became Star-Lord, What If...? returns to explore a reality in which Nick Fury fails to get the Avengers Initiative off the ground. "What If... The World Lost Its Mightiest Heroes" is an alternate take on Fury's Big Week, only this time, things go horribly wrong.
The latest episode of What If...? begins on a Monday during Iron Man 2, just as Nick Fury attempts to recruit Tony Stark into the Avengers Initiative at the donut shop. However, when Black Widow injects Iron Man with the serum that will allow him to fight his illness, he drops dead. The Watcher then explains that, while the events of Fury's Big Week were the catalyst that would form the Avengers, the reality "What If... The World Lost Its Mightiest Heroes" explores takes a different turn.
On Tuesday, Agent Coulson finds Mjolnir in New Mexico, but Fury can't come immediately, as he's overseeing Black Widow's transfer to Alexander Pierce, who wants to interrogate her. But as S.H.I.E.L.D.'s Strike Team, led by Brock Rumlow, takes her away, Fury informs Natasha that he knows she wasn't involved. After being taken away, Natasha makes quick work of her captors and escapes.
Back in New Mexico, Hawkeye and Fury discuss the hammer just as the God of Thunder arrives to reclaim his weapon. And the events play out similar to the events of Thor, with Hawkeye taking to the sky to get eyes on the Asgardian as he tries to lift the hammer. However, once again, things play out differently, as an arrow hits Thor in the heart. Clint Barton claims he didn't fire the shot, but when Fury goes into his cell to talk to him, Hawkeye dies of mysterious circumstances.
It's now Wednesday, and Natasha heads to Culver University to talk to Betty Ross, who she knows can help her uncover what killed Tony. After Betty discovers a small projectile was the cause of the Iron Man's death, Fury calls Natasha and warns her that the members of the Avengers Initiative are being targeted. She finds Bruce Banner in Betty's office and informs him that they need to run.
During a coffee run, Coulson witnesses the Bifrost arrive on Earth and bring the forces of Asgard, including Loki. But just as Fury heads out to confront them, Natasha calls from Virginia, where Thunderbolt Ross has arrived to take out the Hulk. Banner is promptly shot by a mysterious bullet and loses control, while Loki lays waste to S.H.I.E.L.D.'s forces. However, as the Hulk fights Ross' forces, he explodes, marking the death of another potential Avenger. Meanwhile, back in New Mexico, Loki gives Fury one day to find his brother's killer.
Without any leads, Natasha is investigating the Avenger Initiative's files when an invisible assailant attacks her. She's able to leave Fury a message that claims "hope" is at the bottom of the murders, which prompts him to talk to Loki. Fury then heads to Hope Van Dyne's grave in San Fransisco, where he finds a distraught Hank Pym. Hank reveals that after his daughter's death, he swore revenge against Fury, so much so, he devised a plan to destroy his life's work by killing the Avengers.
A conflict between the two ensues, and while it's clear Fury has the upper hand, something is clearly off. It turns out Loki accompanied Fury on his mission and helped him defeat Pym using his magical abilities. However, after their victory, Loki decides to stay on Earth, and, without the Avengers to stop him, he takes it over by the next day. Thankfully, Fury still has a plan to save his world, recruiting Carol Danvers and finding Steve Rogers to try and once again make the Avengers a reality.
To see Earth's Mightiest Heroes fail to form in the MCU, the third episode of What If...? is streaming now on Disney+.