We've heard the rumor that Darkseid will be the villain in Justice League, and that only makes sense. He's a big enough threat, he's well-known enough, and he's not a giant space starfish. Once I heard Darkseid, I assumed he would be involved in some generic plot that would bring the heroes together, sort of like Loki's alien invasion in The Avengers. I certainly never thought the movie would take direct influence from a comic story - let alone a Pre-Crisis comic story.
But according to Latino Review, who also broke Darkseid's identity, the story of the movie comes from a three issue 1980 Justice League of America tale written by Gerry Conway with art by George Perez. In the story Darkseid is attempting to use a beam to knock Earth out of orbit and put his world, Apokolips, in its place. I'm not sure what he hopes to gain, but that's a very, very comic book-y storyline indeed. It's cosmic destruction with low motivation.
What makes this truly interesting is the fact that the story is a crossover between the Justice League and the Justice Society; back in 1980, the Justice League and Justice Society (WWII versions of DC heroes) lived in different dimensions, and they would annually cross between worlds to work together. While I doubt Justice League will actually feature the Justice Society, does this offer us a hint of how the heroes get together?
I'm just spitballing here, but what if screenwriter Will Beale is solving the problem of multiple superheroes by having them live on different Earths? This way the post-Nolan Batman films can maintain their own tone while Warner Bros tries to go bigger with other franchises. Hell, this could handwave away the entire Batman crossover in general - we just accept that Nolan's Batfilms happen on Earth N, while the Justice League team ups happen on Earth JL.
That's probably not the case, but I can't otherwise imagine why this story is being used as the template. The story does heavily feature the New Gods, so there's some hope those characters might show up - but will Warner Bros want to introduce that many new superpowered characters to movie audiences?