Co-directors Joe and Anthony Russo have indicated the start of filming on Avengers 4 with a cryptic new photo from the film's set.

The Russo Brothers posted a mysterious picture on their official Facebook page this afternoon with only the words "Beginning the end" attached to the image. The photo shows a purple glove holding up four fingers to the camera.

It's a simple enough picture, but what does it mean? Are we just four days from a new Avengers: Infinity War teaser? Four days from learning what the title of the film will be? Will Hawkeye have a larger role in this film? Does this signal the end of Phase 3 and the beginning of Phase 4?

More importantly, what is coming to an end? This can't be the end of the Marvel Cinematic Universe, considering a sequel to Spider-Man: Homecoming and Guardians of the Galaxy Vol. 3 are set to be released after the film. Perhaps this will be the final Avengers movie and a new team narrative will take over.

RELATED: Hawkeye Netflix Series Not ‘on the Table,’ Says Jeremy Renner

Filming for the still-untitled Avengers title opened at Pinewood Atlanta Studios in Fayette County, Georgia. It is scheduled to last until December 2017 and will be shot entirely in IMAX format.

When the Russo Brothers came onto the project to direct, Avengers: Infinity Wars was still expected to be a two-part film. Despite the separation of the two movies, filming would remain on a back-to-back schedule. The first movie began production in January and wrapped up in July. Additional filming was conducted in Scotland, England, the Downtown Atlanta area, and New York City.

So far, there has been no new information concerning the plot of Avengers 4 or how it will deal with the aftermath of Infinity War. The film will reportedly see every major plot thread and character arch come to a conclusion in the MCU. Whether this movie will signal an ending or a new beginning is yet to be seen.

The untitled Avengers movie is scheduled for a May 3, 2019 release. Avengers: Infinity War is currently in post-production and is set to see theaters on May 4, 2018, almost exactly one year earlier.

Avengers 4 is expected to return another big cast with Robert Downey Jr., Josh Brolin, Mark Ruffalo, Tom Hiddleston, Chris Evans, Chris Hemsworth, Jeremy Renner, Chris Pratt, Elizabeth Olsen, Benedict Cumberbatch, Samuel L. Jackson, Evangeline Lilly, Karen Gillan, Anthony Mackie, Tom Holland, Zoe Zaldana, and Dave Bautista reprising their respective roles.