4 scientists are transformed into meta-humans as they unite to face a former student, who was raged and was proving to be smarter.
- Ryan Reynolds as Reed Richards/Mr. Fantastic
- Sarah Michelle Geller as Susan Storm/Invisible Woman
- Matt Lanter as Johnny Storm/Human Torch
- Joaquin Phoenix as Ben Grimm/The Thing
- Michael Sheen as Victor von Doom/Dr. Doom
- Wayne Knight as Mole Man
- Samuel L. Jackson as Nick Fury
The film starts with Reed Richards at Empire State University. He enters his room to find his roomate, Victor von Doom, working on a project. He points out an error in his work, but Victor pays no attention to him. Reed soon leaves, but after he leaves, Victor's project explodes and his face is apparently disfigured. He is then expelled and believes that it is all Reed's fault and that he must have tampered with his project and swears revenge against him.
15 years later, Reed is designing a space ship for interstellar travel, but the government stops funding his project. Reed wants to see his project through, so he makes an unscheduled flight test. Although he planned for it to only be him and his best friend, Ben Grimm, going into space, Reed lets his friend, Sue Strom, and her brother, Johnny Storm, come with them. While in space, the four are hit with cosmic rays and gain superhuman abilities. Reed acn stretch into any shape or size, Sue can turn invisible and project force fields, Johnny can control fire, and Ben's skin has been turned into a rock-like substance and he now posseses superhuman strength. Meanwhile, another scientist, Harvey Rupert Elder, discovers a cave leading to the underground realm of Subterranea. He is then partially blinded when he looks directly at a highly reflective deposit of diamonds. He then dubs himself Mole Man and soon after, discovers a branch of Subterraneans called Moloids. He soon becomes the ruler of the Moloids and Subterranea. He later finds technology in Subterranea and plans to use it and his new army to conquer the surface world that rejected him. At Reed's lab, he is trying to find a way to cure them and Ben of their powers, but he is unable to. Soon, they here an explosion. When they go to see what is going on, they find Mole Man attacking the city. They decide to help and are able to defeat Mole Man and his Moloid army. Reed believes that they should take him to prison, but before they can, Nick Fury, director of S.H.I.E.L.D., shows up and takes him to a secret S.H.I.E.L.D. base nearby. While Nick Fury takes Mole Man, someone is watching them. He follows them into the S.H.I.E.L.D. base and is able to free Mole Man. Mole Man then joins forces with this villain, who calls himself Doctor Doom, to get revenge on Reed Richards and the other people who defeated him. After the two head off, Nick Fury finds Reed and the others and asks for their help. They decide to help him and They become the superhero group known as the Fantastic Four, with Reed as Mister Fantastic, Sue as The Invisible Woman, Johnny as The Human Torch, and Ben as The Thing. Meanwhile, Doctor Doom and Mole Man plan to lure out the Fantastic Four with another attack on New York City, then trap them, and finally destroy them. In the end, Doctor Doom and Mole Man are only able to trap Sue, Ben, and Johnny and decide to use them as bait for Reed. The two then lead him back to Doom's Castle in Latveria. When he arrives, Doom tells Mole Man to watch the three heroes while he takes care of Reed. Doom meets with him and the two battle. At one point, Doom reveals to Reed his real identity, Victor von Doom, and that he has planned to take his revenge on Reed ever since he was expelled. The two then continue to battle while Sue, Ben, and Johnny find a way to escape from their prison and defeat Mole Man. Nick Fury then arrives and orders two S.H.I.E.L.D. agents to take him back to the S.H.I.E.L.D. base in New York. The three members of the Fantastic Four then head off to help Reed. Just as it seems that Reed will be killed by Doom, the others come and together, the Fantastic Four are able to defeat Doom. As a last resort, Doom sets his Castle to self destruct, however, the Fantastic Four are saved by Nick Fury when he brings down the S.H.I.E.L.D. Helicarrier and takes the four back to New York while Doom apparently dies in the explosion. When the four of them are dropped off back in New York, Reed and Sue relise they have feelings for each other and kiss.
In a post-credits scene, Doom is revealed to have survived the explosion and plans to take his revenge on the Fantastic Four.