Here is the original World's Finest Batman and Superman story.
The opening scenes involve a terrorist group that has taken over an African village, and in the process mass massacres — men/women/children — were performed in the name of religious supremacy. Amidst the growing terror, news of it gets to the world, and reporters are sent to the scene to investigate. Lois Lane was given access to interview the terrorist leader, but during the interview, passions grow wild. The crew that came with Lois Lane are murdered one by one, except for her and Jimmy Olsen (photographer), due to the fact that the terrorists wanted their story told, and they want Lois and Jimmy to memorialize their conquests. Shortly after the murders, Superman arrives in the village. Superman manages to destroy enemy armory and tanks, essentially running off the terrorist army. Superman ultimately gets to the headquarters and successfully rescues Lois and Jimmy. He returns to the village to rescue innocent villagers, but while doing so the terrorist leader detonates a bomb; killing themselves and taking out hundreds of innocent people in the process.
A UN Congressional Hearing follows with Superman to explain what happened. The UN fears that Superman’s involvement escalated the terrorists’ plans, thereby causing the deaths of innocent civilians. Superman is sanctioned to remain in the U.S. and is asked to no longer intervene in matters of international disputes.
The President of the U.S. (Holly Hunter), who was leading the UN Congressional Hearing, receives a call from Lex Luthor requesting to meet her. Upon privately meeting with Lex, who is a charming, highly respected businessman and philanthropist (at the time Bryan Cranston or Joaquin Phoenix was being eyed for the role), he offers the president access to Kryptonian technology that would weaken Superman in the event he becomes a threat to national security. Lex shares with the President the existence of terraformed crystals found in the Indian Ocean capable of weakening and easily destroying Zod’s corpse body. Interestingly, the President wants nothing to do with utilizing the Kryptonian technology and terraformed rocks, stating that she thinks Superman is good, and that in the wrong hands, such technology can be used for evil. Lex disagrees and the two argue over power and the responsibility of holding power. Lex is angered that the President appears to care less about having technology that would protect the country from an alien and leaves the president with a warning. He taunts her for not being fit as a leader, and states that she is jeopardizing humankind by not taking advantage of his offer.
Scenes between Clark and Lois follow. Clark ponders how someone powerful as he can ignore suffering in a world when he feels he can intervene. Lois encourages him to stay good and not grow weary, that there is still good left in the world, and that he should be the hope that this world needs. During this scene, a news alert is shown on television, and the terrorist group from the beginning of the movie warns the U.S.A. of imminent attack for letting Superman, an “American hero”, intervene in Africa.
The scene changes to Gotham city bay, and the KGBeast is introduced with a group of representatives from the same terrorists introduced earlier in the movie. A transaction involving a small box of crystals occur. Apparently, it will be revealed later that the box contains weapons of mass destruction in the form of the terraformed crystals; alluded to earlier by Lex. The “Kryptonite” apparently can wield enough power that, when detonated, can be almost like a nuclear bomb. Additionally, members of the terrorist group have already infiltrated Gotham and will use these rocks as bombs to wreck havoc; beginning in Gotham City. KGBeast, who has been hired by the terrorist group, takes said army of terrorists to infiltrate Wayne Enterprises. They kill innocent bystanders, kidnap hostages, and detonate a bomb using a Kryptonite crystal; thereby destroying Wayne Enterprises. Apparently the original script has Lucius Fox dying, and news of this gets to Bruce Wayne, who in the script appears to have been thought dead for a few years.
The death of Lucius and the destruction of Wayne Enterprises gets Batman out of retirement and he begins to investigate the cause of the attack. In time, with the help of Alfred, he discovers where the KGBeast and the terrorists are hiding. He dons the Batman costume, a more primitive looking one, and only with a few gadgets. He defeats the terrorists, but not before the KGBeast escapes with the box of kryptonite.
Batman finds a way to contact Superman, and the two meet to discuss the recent terrorist attacks in Africa and Gotham City. Batman informs Superman that he had been a crime fighter many years ago, and that Superman still has a lot to learn. Comedy moment occurs when Batman tells Superman he knows he is Clark Kent, and Superman returns the favor by calling him Bruce. When Superman asks Batman how he knew, Batman said he had his ways. The two leave as friends.
The scene cuts to Lexcorp where the Kryptonian suit, as worn by Zod in 'Man of Steel' is being reproduced in high quantities. Luther’s scientists test them, and they show tremendous power – especially when powered by Kryptonite. One suit in particular has Kryptonite and will be worn later by the KGBeast, who in a way will also act as this movie’s “Metallo.”
Lex leaves the laboratory only to meet privately with the KGBeast. It is revealed that it was Lex who earlier sold the terrorists the Kryptonite crystals that was used to destroy Wayne Enterprises. They discuss their mutual partnership, and Lex reveals his motivations: 1) He wanted Wayne Enterprises knocked off from being competition to his technology empire and 2) He believes the U.S. President is unfit to lead for her refusal to take his offer earlier. He coldly makes the statement that any leader who willfully allows an “alien” to run uncontrolled should be removed from any position of power. KGBeast is promised a package of the “super-suits.” He informs Lex he plans to attack Washington D.C. and kill the President of the United States for him. Lex thinks it’s a good way to test his super suits.
Tensions mount as an attack on Washington D.C. is shown by the now super-powered KGBeast (Metallo revamped), along with a group of terrorists wearing the Kryptonian armor. KGBeast goes straight for the White House and kidnaps the President along with other government officials. This gets the attention of the world, including our heroes. The terrorists wrecks havoc with their Kryptonian armor, destroying monuments, the Capitol building, etc. The pair of heroes arrive; Superman in flight, and Batman in his jet. Together they begin to fight the superpowered terrorists. Batman’s jet is destroyed in the process, and when he comes out, it is revealed he has a power armor of his own with newer gadgets — big bad ass moment for Batman! The two heroes continue to fight the superpowered terrorists and ultimately defeat them. Superman and Batman partner to take down the KGBeast. Batman was left with the task of rescuing the President, while Superman fights the super-powered KGBeast. During this fight, Superman discovers that the KGBeast’s armor is specifically powered with a large kryptonite rock. Superman gets brutally beaten up during this fight, and requires Batman’s help, who too gets pretty beat up by the superpowered terrorist. The two heroes work together to somehow distract the enemy and dislodge the kryptonite rock that powers his suit. A grappling gun is used by Batman to tie up the KGBeast, and while tied up, Superman manages to use human level strength to take down the bad guy. The KGBeast is taken to prison, but prior to being questioned, he is murdered.
As the movie begins to close, you see Batman and Superman talking yet again. Superman hands Batman a box, and inside is kryptonite. Superman asks Batman to have it and to use it if ever he felt the need to be put down. The camera backs up and you see inside a big office a quiet Lex Luthor who is watching the two heroes talking from afar. He puts on a ring of what appears to be ladened with green kryptonite. As the closing music begins to play, the news on television reveals that the President of the U.S. had just been assassinated. Movie ends.