When the Marvel historians document the war between Thanos and the Avengers, they’ll say it all changed on Thursday. That’s when directing duo Joe and Anthony Russo announced the start of filming on Avengers 4, the untitled sequel to Avengers: Infinity War that’s been teased as a game-changer for the Marvel Cinematic Universe of films.

“Beginning the end,” reads a post on their official Facebook page along with a teaser image of a gloved hand holding up four fingers.

The Russos wrapped production on Infinity War shortly before the D23 Expo and San Diego Comic-Con, where the first epic trailer debuted exclusively for the gathered crowds. (Speaking of which, the rest of us are patiently waiting on an official release.) Now the filmmakers are back at it.

The title of Avengers 4 was originally dubbed Avengers: Infinity War – Part 2, but soon dropped the subtitle. It’s new name is still a secret because, as Marvel Studios President Kevin Feige confirmed to CinemaBlend earlier this year, it’s a spoiler of what’s to come.

See the first production teaser below.

“These two movies are intended to be the culmination of everything that has happened in the [Marvel Cinematic Universe] since the very first Iron Man movie,” Anthony Russo said a year ago. “In being a culmination, these movies are in some ways going to be an end to certain things, and in some ways, they’re going to be the beginning of certain things.”

Infinity War will see Josh Brolin portray the “Mad Titan” Thanos and unleash his “children,” The Black Order, in fighting to claim all the Infinity Stones, which have been popping up throughout the prior films. The immense cast features mainstays like Captain America (Chris Evans) and Iron Man (Robert Downey Jr.), newer characters like Spider-Man (Tom Holland) and Black Panther (Chadwick Boseman), the Guardians of the Galaxy (Chris Pratt, Zoe Saldana, Dave Bautista, Bradley Cooper, Vin Diesel, Pom Klementieff), and many more.

Evans also teased that both Infinity War and this next film will “wrap up everything.”

Avengers: Infinity War will hit theaters on May 4, 2018, and Avengers 4 will drop on May 3, 2019.