The CIA has covertly hired Professor Jerry Hathaway at Pacific Technical University to develop the power source for "Crossbow": a laser weapon precise enough to commit illegal political assassinations from outer space. Hathaway uses his position to recruit brilliant students to do the work for him but, aside from his graduate student and toady Kent, does not tell them the reason for their research.

Hathaway's latest prospect is genius high school student Mitch Taylor. Despite his youth and inexperience, Hathaway makes Mitch the lead on the project due to his innovative and original ideas in the field of laser physics. Mitch is roomed with Chris Knight, another member of the team, a legend in the "National Physics Club" and one of Mitch's idols. Mitch's ideal of Chris is shattered, however, when Chris turns out to be more of a goof-off than a hard-working student. Meanwhile, Hathaway hopes Mitch will encourage Chris to straighten up his act and that their two exceptional minds can develop a proper power source.

With the deadline quickly approaching, Mitch feels the pressure to complete the project while Chris continues in his carefree attitude. After inviting Mitch to a pool party to blow off steam, Kent reports this to Hathaway, who lambasts Mitch. Mitch breaks down and tearfully calls his parents, telling them he wants to go home. Kent records the call without Mitch's knowledge and later plays the recording over the school's public address system, humiliating Mitch. As Mitch begins packing to leave, Chris explains about the pressures of school and burdens of being highly intelligent by relating the history of former Pacific Tech student Lazlo Hollyfeld. Lazlo cracked under the pressure and disappeared (actually now living in the university's tunnels beneath Chris and Mitch's closet). Chris, fearing the same could happen to him, learned to lighten up and begin enjoying life. Mitch acquiesces to stay and they exact revenge on Kent by disassembling his car and reassembling it in his dorm room.

Hathaway, angry about the still-incomplete project and Chris's attitude, informs Chris that he intends to fail him in his final course needed for graduation and will give a coveted after-graduation job, originally promised to Chris, to Kent instead, as well as take steps to ensure Chris will never find work in the field of laser physics. Chris is disheartened and Mitch must use Chris's same argument to convince him to stay. The two commit themselves to finishing the 5 megawatt laser and making sure Chris passes Hathaway's final exam.

Kent sabotages their latest, nearly-successful apparatus. Though Chris knows Kent destroyed the laser, he can do nothing about it and is left to brood over the injustice; this inspires him to come up with a whole new system. The new solution works flawlessly, impressing Hathaway; he congratulates Chris and assures him that he will graduate. Chris and Mitch leave and celebrate, but Lazlo arrives to tell them his suspicions regarding the possible uses of such a laser. Realizing he is right, they return to the lab, but all the laser equipment has already been removed by Hathaway.

They surreptitiously implant a radio transmitter in Kent's mouth and use it convince him he is speaking to Jesus. Kent divulges the location of the Air Force base where the equipment has been installed on a B-1 bomber. Chris and Mitch sneak onto the airbase and reprogram the coordinates of the target before going to Hathaway's home to set up a small prism. They gather outside Hathaway's home to watch as another school professor and a Congressman arrive, having been told of the test. Kent arrives and, though he was told by Jesus to remain outside, he goes inside. The laser test begins, with the new target being Hathaway's house. A very large bag of popcorn (Hathaway detests popcorn) is heated by the laser refracted by the prism, filling the house entirely and causing it to burst at the seams, with Kent riding a popcorn wave through the front door. Lazlo arrives in an RV—which he has won using mathematics in a blind sweepstakes contest—to tell them he is leaving. Later, Hathaway arrives to see what has become of his house.
Summarize the plot synopsis of the movie Real Genius in 3 sentences.
The CIA hires Professor Jerry Hathaway to develop the power source for a laser powerful and precise enough to vaporize human targets from outer space. Hathaway's newly recruited genius Mitch, along with his previous prodigy, Chris, work together to develop the technology and succeed, only to later learn of Hathaway's true intention for their work. The students and their friends sabotage their own invention and teach Hathaway a lesson by having the laser to pop an enormous bag of popcorn in Jerry's house, knowing that he hates popcorn.