We open with a flash back of several years ago before the events of man of steel. Here we are introduced to a young Lex luthor at his 18th birthday and at this point he is old enough to take over his parents company and he plans to take advantage of this. he walks into his parents room and shoots both of them dead.
Now in the present day we are at a park and four criminals are violating a city. they are shooting at random people who pass by, they are vandalizing peoples homes and businesses and taking whatever they want. they then hang out at a park after a while and that's where they get there justice. one by one they are dragged into the shadows. until only one is left, he is ready to both run for it and shoot at whoever or whatever is attacking them and then the man appeared to him. he was batman and he killed him.
the next day some where far away a plane is flying with lois lane on it. here we get some exposition that a terrorist group has been attacking all governments of all countries in the americas and now there are no leaders. that's why Lexcorp is funding elections to help the americas recover from this. once we learn this the plane is hit by a missile and is sent falling to it's death until Superman saves it and everyone who was on board.
superman then follows the smoke to the terrorist base and goes to attack them but remembers how bad he felt when he killed general zod. so superman isn't giving it his all because he knows that if he does then he could just kill them all in a split second but because of his restraint some of the terrorists get away.
somewhere else in the americas Lex Luthor (now an adult) is being confronted by a detective who has discovered a terrible truth. Lex Corp is behind all the terrorist attacks! once Lex knows the detective has discovered this he then has his warrior "Nuclear Man" kill the detective.
after lex takes care of that he goes to wayne enterprises where Bruce Wayne is the boss of it and Lex proposes that they combine there businesses (secretly because he's aware that bruce may be batman and wants to get some bat gear for himself) but Bruce says no because his parents wouldn't want there lives work to be handed away but Lex tells him that his parents were also murdered and that they would have to settle there differences.
later on Batman and Superman cross paths as they go after the terrorist and they both take care of them easilly. Superman goes on about how easy it was because of his powers but batman goes on about how awesome his plan was and we build chemistry with the pair of them here.
superman goes to save someone else while batman stays to do some detective work where he too discovers the truth Lexcorp is behind the attacks. he goes to the bat cave with his butler alfred pennyworth who says batman has to go a fight lex luthor but bruce in his wisdom foresees Lex may have some surprises. he decides to throw a party and question Lex casually and subtley there in public. after that they may plan an attack.
in the days that followed both the dark knight and the man of steel must train. they knew the terrorist were still out there and batman knew he had to face the worst one ever. while superman was training though Lex Luthor was able to track him down and find the fortress of solitude. lex then learnt of the secrets of supermans weaknesses and would prepare to exploit them.
Bruce's party came around and Lex did show up. Bruce tried to get basic information out of him bearing in mind it would be a cover story but no subtlety get's past Lex Luthor. he sent an assassin to kill bruce when the party was over but Bruce is Batman so he could take care of himself and kill the assassin. Lex had just given him an advantage, he thought bruce was dead.
the next morning Bruce wasn't drunk. he spent an hour last night developing a plan but it proved unnecessary as Lex Luthor broadcasted all over the americas interupting all radio and TV. He challenged Batman and Superman to a fight.
Lois had absolute faith in superman and Alfred trusted batman to do a good job. the both of them went to Lex's meeting point read to take him when nuclear man turned up ready to fight superman. the 2 super powered being clashed in a battle while the caped crusader went strait for lex Luthor himself and beat him sensless. while this was happening superman was being battered too as he was restraining himself for fear of killing nuclear man and as a result nuclear man beat super man and was able to return and beat batman. both of the worlds finest heroes were locked in a cell were Lex was able to nullify super mans powers.
Batman knew parts of Lex's plan but lex needed to fill both of them in on everything because if there's one thing all smart people have in common. they want to explain why there so clever and as both of them were locked in without a hope of getting out it seemed like there was no harm in telling them.
Lex corp was funding all the elections for all the countries in the americas because all the leaders had been assassinated by the terrorists but what he didn't tell anyone is that Lex Luthor also hired the candidates to run for election and get elected. he had been silencing any competitors and peole who discovered the truth. and once they all got elected Lex Luthor would then irradicate his employees with them thinking they would share the power, and then Lex will rule the continent.
the heroes vowed to stop him but in that cell there was nothing they could do. once Lex left the room Batman got formulating a plan of escape in his head. when he was nearly done he told superman that he had a way but superman was too distracted. the cell they were in was taking away his powers so he felt really hung over because his physical strength, intelligence and other powers were all plummeting. when he felt better he asked batman how he could kill so easilly and Batman answered "sometimes you have to kill the villain not because you hate them but because you care about the good people in danger" and superman could understand that and it helped him. but he also felt the need to tell batman not to let it corrupt him because superman saw an evil within batman that really shows when he's fighting. they contemplated what each other said and they had valuable lessons to learn.
after they spoke with each other Batman did have a plan but he didn't need it as robin came to rescue. he said alfred called that Lex Luthor had challenged batman and superman to a duel and then he never came back. but robin was unaware that a guard saw him and was ready to close to door and lock him in their with them but batman stopped him. he did have a clever plan but now it was time just to use brute force. once superman was out of the cell all his powers came back to him and then he could fight with batman and robin to freedom. he used him telekinesis to restrain and knock out the guards while batman was using his skills to neutralize them and not kill them. now that they were out they decided to go to washington DC and stop the election and save the United States of America as well as the rest of america.
before the heroes turned up Lex was at the elections in Washington DC. he arranged it so that all of america would get the new leaders at the same time. when it was confirmed that he won the election he killed his employee and ordered a hit on all the other fake candidates and at that point Lex ruled all of america, one of the biggest take overs in history. once he had this he unleashed nuclear man to the people and any one who would dare oppose him
but only until Batman and Superman showed up and were ready to take him out. super man went to fight nuclear man while batman went to take out lex but he wasn't prepared for lex to get into his battle armour. batman could still fight lex and superman could still fight nuclear man and it was on. everyone was fighting to the best of their ability. it ended with superman having the guts to kill nuclear man and batman having the skill to beat Lex Luthor without killing him.
but even with the defeat Lex Luthor wasn't done yet and he still had layers to his plan that he didn't tell the heroes. he had back ups in case he failed to gain power and there were cities all over the United States of America with nuclear bombs in them. including Gotham and Metropolis. Superman flew himself to metropolis to stop the bomb while dropping batman off at Gotham on the way. but they weren't just explosives. they had laser cannons on them and these lasers were also able to remove superman's powers and if he got hit the he would die as anyone would. in spite of this he was able to throw the bomb into space and batman was able to deactivate the bomb. but Lex had even more layers to the plan then that. he backed up the nuclear bombs with many smaller explosives all over the cities and when the heroes removed the nuclear bombs all of them went off.
buildings were on fire in not collapsed and many thousands of people were in danger not to mention the many other cities in the country that would get nuced. had the heroes failed? maybe but they still didn't give in they pushed their limits desperately trying to save everyone but it would be hard but they would try it anyway...
the next day they looked back and believed they had done a very good job. not just with what they did but all the other cities had been saved too. maybe they wern't the only heroes in america. but either way as heroes go they did a good job and the villains are taken care off. and without anyone to rule the countries of america the people would need something to keep the peace. they would need something not corruptible by power. they would need a justice league