Doomsday's Doctor Doom hails from Earth-828, the reality inhabited by Marvel's First Family in The Fantastic Four: First Steps. Read on for

First Steps" star Vanessa Kirby breaks down Sue Storm's birth scene and her mid-credits moment with Robert Downey Jr. as Doctor Doom.

In their MCU debut, the Fantastic Four become a Fantastic Five with the arrival of Reed and Sue's son, Franklin Richards. Worries that he might not be "normal" are confirmed in Fantastic Four: First Steps when Galactus recognises that the boy can wield an unlimited energy known as the Power Cosmic (presumably because of the "cosmically compromised DNA" shared by both of his parents).

As Fantastic Four: First Steps heads towards its final act, the group is torn between two impossible choices: sacrifice all of Earth to Galactus, or Reed and Sue must give up their child Franklin, who contains the Power Cosmic and enough energy to satiate Galactus' hunger.

This iteration of the Fantastic Four has a standalone adventure without all the burden of the MCU's history and cast of characters.

First Steps” stormed the domestic box office, topping superhero competitor “Superman” to finish No. 1 with $118 million.

First Steps” is the third Marvel movie to hit theaters this year, but it packs way more hidden references and nods than “Captain America: Brave New World” or “Thunderbolts.” It’s not on the same level of Easter eggs as last year’s “Deadpool and Wolverine,

First Steps cast revealed which Marvel characters they’d recruit to join their team, naming several surprising X-Men picks. While Black Panther and Spider-Man were popular choices, Mystique stood out as a favorite among the cast.