I know the entire plot of JL. Ask me anything. [SPOILERS]

Opens with kids recording Superman on their phone. They ask him what his favorite thing about Earth is. He smiles. Title card. Montage of the world mourning Superman and crime on the rise. Then you get Batman and Wonder Woman off doing their own thing. They both become aware that Steppenwolf has come to Earth (he invades Themyscira first and steals their Mother Box). They go off to recruit. Cyborg and Aquaman say no. Flash says yes. Parademons kidnap Cyborg's dad. Steppenwolf invades Atlantis and takes their Mother Box. Batman, Wonder Woman, and Flash meet Gordon to talk about a Parademon nest in the tunnel between Gotham and Metropolis. Cyborg joins them because he wants to find his dad. They go into the tunnel and have a fight. Aquaman saves their butts when the tunnel is flooded. End of Act 1.

The League decides that they need Superman. They deduce that they can use the Mother Box that Cyborg has to revive him (since these things are so powerful). The problem is that Cyborg's Mother Box is "dead" (since it used up it's power to create him). But they figure out that Flash can somehow "recharge" it. They dig up Superman's coffin and take it to the Scout Ship in Metropolis. Flash's charge thing works and Superman comes back to life. He's confused and attacks Batman. When he sees Lois (who Bruce told to be there to calm him down), he flies off with her to the Kent farm. The League realizes that Superman isn't quite ready to rejoin the fight. End of Act 2.

The final part of the movie is basically the Justice League trying to hold off Steppenwolf (at his HQ in Chernobyl) until Superman can fully return. Clark spends a good deal of time "debriefing" at the Kent Farm before he makes his epic return to help the team stop Steppenwolf for good. Lois gives a VO about the world needing heroes and we get a montage of the team going back to their regular lives.