Superman IV: The Quest for PeaceSave

Clark Kent (Christopher Reeve) is returning to the Daily Planet after a long absence, where he's joined by new editor Perry White (Jackie Cooper) and his old colleague Lois Lane (Margot Kidder, returning after her reduced Superman III appearance). Perry has just sold the Daily Planet to David Warfield (Sam Wanamaker), a sleazy tabloid mogul who wants to transform the paper into a sensationalist outlet. Warfield's daughter Lacy (Mariel Hemingway) is being inserted into the newsroom as a Hollywood-style romantic foil for Clark. Lois, increasingly alienated by the tabloid direction, considers leaving.

The film's central plot is triggered by a letter from a schoolboy named Jeremy (Damian McLawhorn) asking Superman to rid the world of all nuclear weapons. Clark, after considerable deliberation, decides to comply: as Superman, he gathers every nuclear missile on Earth, packs them into a giant cosmic net, and hurls the net into the sun. Multiple nation-states publicly protest — but the threat of nuclear war is effectively eliminated. Lex Luthor (Gene Hackman), having escaped prison again, sees opportunity in Superman's well-intentioned disarmament.

Luthor escapes prison with the help of his nephew Lenny (Jon Cryer in his early-career role) and immediately begins selling nuclear secrets to terrorist groups internationally. To eliminate Superman's interference, Luthor steals one of Superman's hairs from the Metropolis Museum (where it's enshrined as a national exhibit) and combines it with energy harvested from a stolen Soviet nuclear missile. Luthor uses the combination to grow a Kryptonian-DNA-based clone he calls 'Nuclear Man' (Mark Pillow). Nuclear Man is, in effect, an evil Superman powered by solar energy.

Nuclear Man's first attack on Earth involves a global crisis manufactured by Luthor — destroying a major bridge, threatening major monuments, and forcing Superman to engage him in direct combat. Their fight is staged across multiple iconic global locations: the Eiffel Tower, the Great Wall of China, Mount Vesuvius, and the Moon. The fight is the film's most-cited visual setpiece, though the production's budget constraints meant that approximately half of the planned action scenes were either trimmed or filmed with significantly compromised effects.

Nuclear Man's defeat requires Superman to use his powers in unusual ways. Nuclear Man's energy source is the sun; Superman discovers that depriving Nuclear Man of sunlight will deactivate him. The third-act fight on the Moon sees Superman dragging Nuclear Man into the lunar shadow; Nuclear Man deactivates. The Moon location was filmed at the Pinewood Studios soundstage with practical lunar-surface props; the limited budget meant the lunar sequence used a smaller-than-planned set.

Lex Luthor is recaptured at the end of the film. Nuclear Man is permanently deactivated; his body is buried in deep space. Superman gives a televised address to the United Nations, withdrawing from his disarmament commitment — he tells the world that he was wrong to make the decision unilaterally, that humanity must decide its own future on nuclear weapons. The film's epilogue brings Clark and Lois into a quiet moment at the Daily Planet, with the threat of corporate tabloidisation defeated through Lacy's eventual betrayal of her own father.