SPOILER WARNING: This article contains major spoilers for "Lockup," the latest episode of "Agents of S.H.I.E.L.D."

In "Lockup," the Darkhold officially arrived on "Agents of S.H.I.E.L.D." With a quick flashback, the episode followed Lucy and her husband as they discovered it in the basement of the person who killed the book's previous owner. As they descended into the dark basement, they encountered a room filled with all manner of storage -- and a handful of Quentin Carnival posters lining the walls.

If you're wondering what Quentin Carnival has to do with anything that's gone down in "Agents of S.H.I.E.L.D." Season 4 so far, it all comes down to a man named Johnny Blaze. Debuting in 1972's "Marvel Spotlight" #5, Blaze became the first comic book character character to take on the Ghost Rider mantle; bonded with the Spirit of Vengeance, Blaze punished the wicked with his Penance Stare, burning the soul of his victim without leaving any physical markers. Notably, "Agents of S.H.I.E.L.D.'s" Robbie Reyes was also said to burn the soul of several Watchdogs in the Season 4 premiere.

In the comics, Blaze was born and raised at the Quentin Carnival, a popular traveling festival. There, Blaze became a stunt motorcycle driver, though he left it behind to protect its members from the wrath of the Ghost Rider after he struck a deal with Mephisto for the life of his foster father. Nevertheless, he has returned to the Carnival several times throughout his tenure as the Spirit of Vengeance.

While the posters in "Lockup" don't confirm Blaze's existence in the Marvel Cinematic Universe, they mean that key components of his mythology do. Additionally, the identity of person who had possession of the Darkhold before Lucy was never revealed. At this point, however, it's unclear if this will be expanded upon or left as an Easter egg for Marvel Comics fans.

UPDATE: As spotted by ComicsAlliance, that Quentin Carnival poster isn't the only Johnny Blaze hint dropped in that opening scene. As Lucy and her husband move through the basement, they pass by a handful of storage items -- including a leather jacket, motorcycle and motorcycle helmets. Though this is far from proof that Johnny Blaze originally possessed the Darkhold, it does heavily hint that he did.

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Airing Tuesdays at 10 pm ET/PT on ABC, "Marvel's Agents of S.H.I.E.L.D." stars Clark Gregg as Agent Phil Coulson, Chloe Bennet as Daisy "Quake" Johnson, Ming-Na Wen as Melinda May, Iain De Caestecker as Leo Fitz, Elizabeth Henstridge as Jemma Simmons, Henry Simmons as Alphonso "Mack" Mackenzie and more.