Marvel's Hall H Press Line For 'Ant-Man' And 'Avengers: Age Of Ultron'Also, why is Tony Stark now blond? First Black Widow, now Iron Man. Hulk, you're next!

"Avengers 4" is still filming in Atlanta, at least for some actors, and new photos recently leaked from set. They are very mysterious and intriguing, and fans have been speculating the *language* out of them.

In the pics, we clearly see Captain America (Chris Evans) -- but clean-shaven and in his old suit, like we haven't seen in a few years. That's Clue No. 1. We also see a blond Tony Stark (Robert Downey, Jr.) apparently wearing a S.H.I.E.L.D. logo. That's Clue No. 2. And all four characters shown in various photos -- Cap, Tony, and also Scott Lang/Ant-Man (Paul Rudd), and Bruce Banner/Hulk (Mark Ruffalo) -- seem to be wearing similar gadgets on their wrists. Clue No. 3.

Put together, a few fans suspect Stark and whoever else traveled back in time to connect with Cap in the past. Maybe. And even if so -- why, specifically? To warn him about something? Save him, if possible? Just get his help but not save him? There's speculation that Cap is not long for this world, but at least he's here right now, so we'll see how it all plays out. We won't see until 2019, though.

Check out some photos, and join the conversations in various tweet comments if you want to weigh in or just see what fans are thinking:

A lot will be cleared up once "Avengers 3," aka "Infinity War," opens in theaters this May 4. We will get the official title of "Avengers 4" after that movie. (It's too spoilery to reveal now.) The fourth "Avengers" movie opens May 3, 2019.

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