Marvel is keeping almost everything about "Avengers 4" close to its proverbial chest. Even the title of the film itself is being kept under wraps, and by the looks of it, fans will not know what the phase 3 capper will be called until sometime after "Avengers: Infinity War."

Speaking on the Happy Sad Confused podcast, directing duo, Joe and Anthony Russo, explained the title would be a spoiler of sorts that would give something away about the third installment if revealed early. "It is certainly part of the concept of the title is that it's advancing the narrative," Joe said. "So we're gonna sit on that until we feel the time is right and when people have absorbed the first movie enough.

The brothers did not say when exactly they will pull the covers off of the title. It was previously expected to be unveiled as part of the "Infinity War" post-credit sequence, but with Joe's statement, that seems unlikely now. If that were the case, it would leak the title online as soon as the first set of previews screenings, and the Russos would not want that to happen. If anything, they may wait until everyone is done with "Infinity War" before they make the announcement.

At this point, not much is known about "Avengers 4," although set photos that popped up online are pointing to a time travel plot. A popular theory posits MCU's mightiest superheroes would travel back in time to defeat the Mad Titan Thanos (Josh Brolin).

Anthony Russo says he is a "big fan of the technique," but he says those photos might not have been what they seemed. The only hint the directors gave is to start looking for clues in different places: "Certainly, there is a five minute sequence in Civil War around a piece of technology that was laid in for a very specific reason. If you go back and look at that film, you may get a hint as to the direction."

According to Cinema Blend, Anthony is referring to the Binary Augmented Retro-Framing, a.k.a. B.A.R.F. This is the technology Tony Stark (Robert Downey Jr.) presented at the MIT in "Captain America: Civil War," which revisited his memory with his parents before they died. BARF would explain the "flashback" photos including the clean-shaven Steve Rogers (Chris Evans).

Then again, this could simply be a piece of misdirection from the Russo brothers. Marvel is notorious for being tight-lipped about unreleased films, so any hints dropped ahead of the premiere should be taken with a grain of salt.

"Avengers 4" is set to hit theaters on May 3, 2019.