Marvel's Falcon & Winter Soldier series could be key setup for this year's The Eternals movie. 2020 is the beginning of the MCU's Phase 4, with the shared universe expanding in more blockbuster movies and a range of Disney+ TV shows. Marvel Studios has committed to a transmedia approach, meaning that these are expected to interlink as never before.

In some cases, the connections are pretty obvious. WandaVision features Elizabeth Olsen, and is expected to be important setup for her role in Doctor Strange in the Multiverse of Madness. Likewise, there have been reports that Loki will explain the return of Mjolnir to the MCU, ahead of Natalie Portman's Jane Foster proving worthy to wield the hammer in Thor: Love and Thunder.

Related: Marvel's Disney+ Shows Are Already Avoiding Netflix MCU Mistakes

There's one Disney+ TV show that stands out, though. Where the others are clearly connected to the MCU's future direction, Falcon & Winter Soldier doesn't have any obvious link. But recent set photos may have given an important clue.

Falcon & Winter Soldier Could Introduce The Ebony Blade

Black Knight With The Ebony Blade

A recent set photo hinted that Falcon & Winter Soldier will head to the fictional island nation of Madripoor. This is the first hint that there'll be a global dimension to the story, and it's particularly interesting because Madripoor is commonly associated with the X-Men comics. It was fleshed out the most in Chris Claremont's Wolverine comics, where Logan settled down there for a time and attempted to tame the crime-ridden island. In fact, the set photo itself corresponds pretty well to the Royal Palace Gardens as seen in 1988's Wolverine #6, which explains why there's a Madripoor flag on display; this is an official residence. Of course, at this stage it's impossible to say just how important a location Madripoor will be in Falcon & Winter Soldier. It could be that this is just a momentary glimpse of the country; alternatively, Sam and Bucky may have to spend some time there. Regardless, the similarity between the set and the Royal Palace Gardens strongly suggests that the MCU's portrayal of Madripoor will be influenced by some classic Wolverine comics.

1988's Wolverine #1-3 saw Logan caught up in events involving a mystical sword referred to as the "Black Blade." This ancient sword had acquired a blood curse, and as a result anyone who held it would come under the thrall of a bloodthirsty and vengeful spirit. Certain people, however, were resistant to to the Black Blade's curse; one notable example was the Silver Samurai. The Black Blade is perfectly analogous to the Black Knight's Ebony Blade, to the extent that they frankly appear to be one and the same thing, just referred to by different names. It's thus possible Falcon & Winter Soldier will introduce the Ebony Blade into the MCU.

The Ebony Blade Could Be Key To Baron Zemo's Plans

Helmut Zemo holds a golden cup in his hand

Falcon & Winter Soldier features the return of Daniel Brühl as Baron Zemo, the man whose plans proved so successful in Captain America: Civil War. The MCU's Baron Zemo has traditionally been portrayed differently to the comics - he's a former Sokovian soldier who lost his family in Avengers: Age of Ultron, and who is seeking revenge upon the Avengers. Still, Marvel has been clear that they're moving him a little closer to the comics, right down to showing photos of him donning a distinctive purple mask.

Related: What MCU Zemo's Mask Will Look Like In The Falcon & Winter Soldier Series

The Baron Zemo of the comics is a prodigious swordsman, well trained in the art of fencing, and he frequently uses a rapier as a weapon. In fact, when Zemo created a fake superhero identity in order to lead the Thunderbolts, he chose to become the swordsman named "Citizen V." While Zemo has never shown a specific interest in the Ebony Blade in the comics, it's not hard to imagine a scenario where he sought it out. This is, after all, an enchanted sword forged by Merlin himself from the Starstone, a meteorite that fell to Earth centuries ago. Some have even theorized that the Ebony Blade is fashioned from Vibranium, the same extraterrestrial substance that gives Captain America's shield its strength. No doubt Zemo would be quite interested in a weapon that is potentially able to cut through that shield.

The Ebony Blade Is Confirmed For The Eternals

Game of Thrones Kit Harington Marvel Black Knight

As noted, the Ebony Blade was fashioned by Merlin in the days of King Arthur and Camelot. He gave it to Sir Percy of Scandia, star of a sword-and-sorcery book by the late, great Stan Lee and artist Joe Maneely. Although the original Black Knight run only lasted five issues, Lee liked the concept, and chose to incorporate it into his superhero comics in the '60s. He revealed that the Ebony Blade had been passed down through the generations; it was initially wielded by a criminal called Nathan Garrett, and in 1967 Roy Thomas had the mantle passed on to the heroic Dane Whitman as the most well-known Black Knight.

Dane Whitman is set to make his own MCU debut in Eternals, with Game of Thrones' Kit Harington playing Black Knight. While Eternals is confirmed to span millennia, it's reasonable to assume that the portions involving Dane Whitman will be set in the present day, given he's typically an ally of the Avengers - and has even led the team on occasion. Falcon & Winter Soldier could introduce the Ebony Blade and its blood curse, with Baron Zemo seeking it out as a potential weapon to use against Steve Rogers' replacement as Captain America.

The Eternals could then retrieve it in their own film, and take it to Black Knight, aware of his family history and the fact he'd be able to resist the blood curse. This theory would neatly explain why Marvel believe the time is right for the Falcon & Winter Soldier series; because it has stronger connections to the upcoming films than had previously been believed. Rather than establishing character arcs for the movies, it's actually an exercise in world-building, helping prepare viewers for a new sword-and-sorcery element that's about to become a major part of the MCU.

More: Doctor Strange 2: Why Black Knight Should Be In The Multiverse Of Madness

Key Release Dates