Warning: this story contains spoilers.

While the very title of the forthcoming DC movie Batman V Superman: Dawn of Justice implies that the two legendary superheroes aren’t going to be fighting on the same side, specific reasons for the conflict have been less certain. But now a synopsis for the film has been released, shedding some light on the matter.

As reported by Den of Geek, Odeon Cinemas in the UK have published a short plot description on their website, in advance of the film’s release in March next year. It reads:

At long last, see Batman and Superman square off against each other in ‘Batman V Superman: Dawn Of Justice’, an epic superhero showdown which will change both their lives forever.

Clark Kent doesn’t trust Gotham’s mysterious masked vigilante. Bruce Wayne doesn’t trust the alien who nearly destroyed Metropolis. And Lex Luthor, who hates Superman more than anyone, is manipulating both of them for his own twisted ends.

Although it has long been known that Lex Luthor would feature as the movie’s main villain, his part in the superhero showdown has been unclear. But this suggests that the central rivalry is very much one of his making.

Jesse Eisenberg plays Luthor in the movie, which is directed by Man of Steel‘s Zack Snyder. Earlier this month, Fortune magazine featured a fictional profile of the villainous businessman, in which he discusses his rivals, including Wayne Enterprises. “It’s not a competition. Besides, I can’t hold a candle to those guys in the debauched billionaire playboy department!” he said.

Batman v Superman: Dawn of Justice will open on March 25, 2016. It stars Ben Affleck as Batman, Henry Cavill as Superman, and Gal Gadot as Wonder Woman. For new images form the film, click here.