There's a hidden message coded on the cover of Captain America: Sentinel of Liberty #4

Captain America: Sentinel of Liberty #4 arrives in September, and Marvel Comics has just revealed the issue's cover from series artist Carmen Carnero, which apparently includes a key to solving part of the mystery that launches in June 15's Captain America: Sentinel of Liberty #1.

Captain America: Sentinel of Liberty stars Steve Rogers in the title role, while a sister title, Captain America: Symbol of Truth, features Sam Wilson also operating as Captain America with his own shield. And it's Steve's original Captain America shield that apparently lies at the heart of the mystery in his new title, as a villainous group known as the Outer Circle will target Steve due to some connection they have to his shield.

The first clue to that connection comes in the form of a code spread throughout the cover, notably in the string of letters and numbers on the left side of the image (no, we haven't cracked it yet ourselves).

Alongside Marvel's release of the Captain America: Sentinel of Liberty #4, the official Captain America Twitter account posted a brief video promising more clues to the code in June 15's Sentinel of Liberty #1. The video flashes a coded message, briefly switching the code to a message that states "Their gameboard is civilization." Perhaps that translation is the key to cracking the code.

The tweet itself includes the text "The Winter Soldier holds the key in the heart of the Devil's Reign." The reference to the recent Devil's Reign crossover seems to indicate that the action will be focused on New York City, the setting of the recently concluded story. This seems to be confirmed in Marvel's press release for the cover, which states that "something is stalking Steve Rogers through the streets of Manhattan."

Here's the video:

As implied by the text of the tweet included with the video, Steve's long-time partner Bucky Barnes, the Winter Soldier, is also wrapped up in the mystery of Captain America: Sentinel of Liberty - and Marvel states that Bucky "knows more about the sinister Outer Circle than Steve realized."

Keep your eyes peeled for the clues Marvel states will be in June 15's Captain America: Sentinel of Liberty #1, and make sure to chime in on Twitter and Facebook if you manage to crack the code.

Marvel's full September 2022 solicitations will be released later this month.

Take an in-depth look at the history of Captain America's shield or Newsarama's list of the best Captain America shield-bearers of all time.