The latest episode of What If…? - titled "What If... Captain Carter Fought The HYDRA Stomper?" - begins at the Battle of New York, but there are a couple of key changes.
As this is the reality where Peggy Carter took the Super Soldier serum in place of Steve Rogers, she’s leading The Avengers and The Hulk has, for reasons which aren’t made clear, been replaced by The Wasp. It’s also Cap and Black Widow who take down Loki!
We later get a new spin on Captain America: The Winter Soldier and revisit the scene we first saw in What If…? season one when Peggy discovers the HYDRA Stomper and the man she fell for when they fought alongside each other World War II, Steve. Unfortunately, it’s not a happy reunion as the armoured veteran attacks her and Natasha Romanoff, and while Captain Carter catches a glimpse of the man she loves, he blasts off into the distance, seemingly unaware of their connection.
It’s revealed that Steve and Bucky Barnes spent years attacking and destroying HYDRA bases after the war, though the former was believed to have perished in the early 50s.
However, the Red Room captured Steve and, in the present day, we find an elderly Bucky at the Triskelion where he now has Alexander Pierce’s Earth-616 gig. He comes under attack from the HYDRA Stomper and, despite Nick Fury ordering Black Widow to kill Steve, she refuses after the brainwashed hero hesitates and decides not to kill Bucky when he comes face-to-face with his old pal.
He may have regained his senses, but Peggy and Steve don’t get too much time to catch up; during their conversation, we learn the Red Room has been activating the HYDRA Stomper on and off over the years, with only the suit now keeping him alive. Heading to Sokovia for answers, they and Natasha are confronted by Melina - suited up as Iron Maiden, sans mask - and her Red Room operatives.
Steve was, and likely has been, under her control this entire time and, following an epic battle against the HYDRA Stomper and Melina’s Widows, Peggy pleads with him to remember his past and the man he once was. It’s a little ambiguous, but some sort of recognition of his previous life seems to kick in, and Steve flies into the Red Room, taking Melina with him, destroying the base and himself in the process.
Despite that, Peggy is confident he survived and vows to find him…until she’s suddenly pulled back in time where she’s met by Variants of Nick Fury and Wanda Maximoff who require her help saving their world. The Watcher is baffled, but this appears to be the year 1602!
When it comes to returning cast members, we have Hayley Atwell as Peggy Carter, Samuel L. Jackson as Nick Fury, Frank Grillo as Brock Rumlow, Sebastian Stan as Bucky Barnes, Elizabeth Olsen as "Wanda-Merlin," and Rachel Weisz as Melina.
The recast roles include Josh Keaton as Steve Rogers and Lake Bell as Black Widow.