"X-Men: Days of Future Past" is riding high right now. This past weekend, the film hit a total worldwide gross of $712.7 million, making it the highest-grossing film of the year so far (although "Transformers: Age of Extinction" may knock it off the top spot in time).

And Fox is capitalizing on that success early, as the film's follow-up, "X-Men: Apocalypse," is already underway.

Just yesterday, director Bryan Singer posted the first page of his treatment for the X-Men sequel to Instagram, teasing X-Men fans with the classic comic villain, Apocalypse, an immortal mutant with god-like powers and a desire to conquer the world.

There's little information to be found in the image- Singer only shows a few chunks of description- but it's clear that the film will open on a large battle scene set in ancient Egypt and featuring the Four Horsemen. The Horsemen of Apocalypse are a team of four supervillains based off the biblical Four Horsemen- Pestilence, War, Death and Famine- who serve the villain Apocalypse in Marvel comics.

These characters were teased in the post-credits sequence for "X-Men: Days of Future Past," which saw a young Apocalypse assemble a pyramid with his mind, flanked by the Four Horsemen. The adult Apocalypse, however, has not been cast- expect a big-name actor to take that role.

This is a good time for Singer, who was recently accused of sexual abuse and was rumored to have been fired from all future X-Men films, despite his crucial role in the franchise (Singer directed the first two films, along with "Days of Future Past").

But considering that he's hard at work writing the sequel, it seems doubtful that the abuse allegations have had any sway with Fox.

"X-Men: Apocalypse" will be a direct follow-up to "Days of Future Past," and follow the '70s-era X-Men team into the 1980s. The film hits theaters on May 27, 2016.