{Cast}
Superman/Clark Kent: Brandon Routh
Batman/Bruce Wayne: Christian Bale
Wonder Woman/Diana Prince: Morena Baccarin
Flash/Wally West: Ryan Reynolds
Green Lantern/Hal Jordan: Ben Browder
Martian Manhunter/J'onn J'onnz: Christopher Judge/Alan Cumming
Lex Luthor: Kevin Spacey
Vandal Savage: Gerard Butler
{Plot}
Centuries ago, we're given a brief introduction of Vandal Savage and his history. He later grows to become the would be conqueror of Themyscira (which has just recently become involved with Martians who have supported them with technology). Vandal tries to seize their powerful weapon, but is stopped and hides decides to move on to other things for now. Modern time, Lex Luthor has recently been announced President of the US and Vandal Savage is Secretary of Defense. Meanwhile Clark has been having strange visions lately. He goes to have lunch with new friend Bruce Wayne towards the end of their conversation, it is revealed to the audience that their secret identities are known between them do to a previous meeting shown in a flashback.Clark tells Bruce about the dreams, and as they get stronger, they go to investigate. Meanwhile, Ambassador Queen Hippolyta and her daughter Diana Princess of Themyscira are contemplating the US on whether or not they should become allies after it's existence has been revealed long ago. During this, clips of Wally West just retiring his Kid Flash costume and helming the new Flash costume are shown , as well as clips of fight pilot Hal Jordan whom already has his ring but doesnt know exactly what to do with it.
Superman and Batman go to investigate the dreams and see that they are coming from the Martian J'onn J'onnz. They help him escape a government testing site and he tells them the story of Vandal Savage after discovering that the man wants to try and open war between Themyscira and the US to retreave the weapon.
Superman and J'onn (now in a different form) talk to president Luthor, who has already had a talking to with Vandal the two are secretly already working together making a Doomsday Weapon to take out all opposing nations and ultimately take control of the world. The president starts war between the Amazon Island and begins rallying troops and he also drafts Superman, J'onn and Wally West joins the fight. Joining them as well is fighter pilot Hal Jordan, with the power ring of course. Upon reaching Themyscira, they're attacked by scouts one being Princess Diana.
Meanwhile, Batman is busy battling Vandal Savage who has begun breaking out a number of criminals from prison to help him as he double crosses Lex to seize the weapon for himself. the heroes on Themyscira are defeated and quickly return, with Diana following. They all apologize for the battle, and then they talk. Soon, Lex brands the heroes as traitors to the country and wanted men and women, including Diana. After meeting up with Batman, they figure out they must band together to stop the war.
The Amazons declare war, and when Diana declines helping, she is branded a traitor as well and the heroes then begin to fight both sides. As war finds its ways to the U.S. Hal dons a costume created by the ring blending in with his fighter pilot suit, and Diana creates a costume out of the American flag to gain trust. Later on, she's mistakenly dubbed "Wonder Woman" by some old folks who watched her save a civilian .Vandal makes it to Liberty Island with the Doomsday Weapon, but Batman and Wonder Woman intervene, and are temporarily knocked unconcious by hidden goons as he finally takes control of the large doomsday weapon. As troops from both sides are defeated, Vandal enters the seen and powers up the missle, powering it up slowly but as fast as it can. Green Lantern notices the weapon powering up from the corner of his eye knocks out the person he's fighting quickly and fly's to it. Flash and Superman rush to the White House to impeach Lex cause of his actions they enter to find that the Oval Office is empty suddenly Lex pops up and attacks Superman with a robotic glove powered by kryptonite knocking him unconcious. Cut to Green Lantern rushing for the weapon, he swoops to the torch of the Statue of Liberty (cut to slo mo cam) he pick's off Vandal sacks him off the Statue of Liberty Vandal falls to his demise on the ground of the island. Hal quickly realizes that he forgot about the weapon and fly's back only to see Batman has already disabled the missle. Cut back to the White House where The Flash is circling around Lex punching him furiously in every inch of his body he stop's to gloat in front of the door then suddenly the door swings open and knocks The Flash in the back of the head one of Lex's secretaries came to see was he alright "Ouch" The Flash said distracted by the bump to the head Lex notices this and uppercuts The Flash and he soars to the wall outside of the door "Thats gonna leave a mark" he says jokingly and then passes out. The Green Lantern and Batman arrive carrying Wonder Woman who is still unconcious Lex notices them through the window and flees to the secret Presidential escape underground the White House Green Lantern notices Flash lying unconcious in the hallway and go's to try to wake him up. Batman sees that Lex is not in the Office and figures he would most likely try to escape through the presidential train underground but is baffled on how to catch him "I can fly after him" says Green Lantern but Batman says that he would be far gone as soon as he gets down there because he's traveling in a bullet train. "I can catch him" says Flash just awakening "He thrashed the suit now it's personal" then he zooms off chasing after the bullet train. Cut back to the office "Thats some kid" says Superman just awakening Wonder Woman sigh's just awakening as well back to The Flash comming up on the train he leaps for the back door misses, trips and tumbles he gets back up "Gotta catch that train" picks up more speed than before and grabs onto the back door handle enters the train and makes his way to the front. The conductor informs Lex that the back door hatch has been opened and someone else is on the train so Lex turns the tables by shutting off all the lights on the train confused The Flash looks around and walks calmly and protectively just to be safe he makes his way to the front of the train to see that its on auto pilot and the conductor lying in the corner then Lex surprises Flash with a gun to his head "Lets see how fast you really are". (Cut to slo mo again ) Flash ducks and dodges the bullet, grabs the gun from behind him, twists Lex's wrist so he drops the gun, and kicks him to cause him to fly backwards and hit a table knocking him unconcious. The train then stops somewhere near Washington (the state) where The Flash uses the CB radio to contact Batman and tell him that everything was fine and he was on his way back with Lex Luthor. In the end, the heroes are awarded medals and Lex Luthor is impeached and thrown in a maximum security prison. The Vice President then takes his new position as President Peter Ross then presents the new team to the world as the Justice League of America.