Reed is a genius convenience store clerk with Ben. Reed's parents don't care about him, and Ben's dad is abusive. They're good friends and have each other's backs. Reed writes a paper for community college on teleportation that attracts the attention of Dr. Franklin Storm, CEO of the Baxter Building research center.
Storm has a son, Johnny, and an adoptive daughter, Sue, whose father, Storm's old partner, died in an experiment gone wrong. Johnny and Sue are party kids, and Sue is particularly disdainful of science. Reed and Sue don't get along at first.
Victor Doomashev is a anti-social Eastern European computer programmer and hacktivist who calls himself "Doom". He hates the 1%, particularly Storm, whom he claims corrupts science for profit.
Storm uses Reed's paper to complete some equations on a machine to access another dimension, the N-Zone. Reed invites Ben to watch the machine being turned on. Sue and Johnny are also there. Doom manages to hack into the Baxter Building's servers and use a computer virus to damage the machine, which explodes. Reed, Sue, Johnny and Ben are exposed to otherwordly energy and become mutants with powers that they can't control.
Storm takes them to the Baxter Building and creates containment suits for their powers. They begin to train. Reed and Storm also begin developing a way to revert the accident. Sue blames Reed for everything, but they eventually become friends and then a couple. Ben can switch off his powers when he's not in danger. Johnny changes colors based on heat intensity, and Sue has some borderline telekinetic thing. Reed is pretty much Reed.
Doom finds out that the four have acquired powers and becomes angry it's not him, so he comes up with a plan to break into the Baxter Building to access the N-Zone through the rebuild machine. As a distraction, he reprograms a bunch of stolen military drones, the "Doombots", to attack the building. The four come together as a team for the first time and save people.
Doom activates the machine and gets technopathy powers or something, basically energy blasts and making machines obey to him, and a fight ensues. The machine goes critical, and, in order to prevent it from exploding and destroying the city, the four push into it and Storm shuts it off.
There's a countdown before it reaches critical mass. Inside the N-Zone, the four battle Doom again, and manage to leave him trapped there after he disfigures himself soaking up too much power. The Four manage to escape, but Ben gets the blunt of it to protect Reed and can't switch back.
The machine is destroyed, Doom is gone, the four have learned to work as a team, and Reed vows to find a cure for Ben. And it ends there.