Stephen Furst

Four mental patients on a field trip in New York City must save their caring chaperon, who ends up being taken to a hospital in a coma after accidentally witnessing a murder, before the killers can find him and finish the job. Dr. Weitzman works with patients in a sanitarium. Convinced that all that his "group" needs is a some fresh air and some time away from the sanitarium, he persuades the administration to allow him to take them to a ballgame. Unfortunately, he accidentally stumbles across a crime in progress and ends up in hospital. The group is stranded in New York City, forced to cope with a place which is often more bizarre than their sanitarium.

In a small Texas town, mentally ill Vietnam veteran John Kirby (Brian Libby) goes insane and kills two people of a family he was staying with. Sheriff Dan Stevens (Chuck Norris) and his deputy Charlie (Stephen Furst) responds and eventually arrests Kirby, but Kirby breaks out of the handcuffs, hits other officers and grabs one of their guns, forcing the officers to open fire and shoot Kirby. Kirby suffers severe gunshot wounds and is near death. Kirby is transported to an institute where his psychiatrist, Tom Halman (Ron Silver), works along with Medical Doctors Spires and Vaughn (Steven Keats and William Finley respectively), who are also genetic engineers. In an attempt to save Kirby, Dr. Spires suggests that they use the formula they created. However, Dr. Halman objects in light of Kirby's psychosis. Dr. Spires first decides that Halman is right, but then ignores the consequences and proceeds to use the formula once Dr. Halman leaves. The formula makes Kirby nearly invulnerable, leading to the deaths of many more people (which includes Halman and his wife, the two doctors who revived him and Charlie). Sheriff Stevens tracks down Kirby in the hope that he can put an end to the carnage. He finally finds Kirby and is able to throw him down a well. As Stevens leaves, however, Kirby's head comes out of the water, meaning he was not killed, at which point the film ends.

In 1962, college freshmen Lawrence "Larry" Kroger (Tom Hulce) and Kent Dorfman (Stephen Furst) seek to join a fraternity at Faber College. They visit the prestigious Omega Theta Pi House's invitational party, but are not welcomed there. They then try next door at Delta Tau Chi House, the campus' most raucous and undisciplined fraternity, where Kent's brother was once a member, making Kent a "legacy." There they find the slovenly John "Bluto" Blutarsky (John Belushi) urinating outside the fraternity house and a wild party already underway inside. The Deltas "need the dues" so they permit Larry and Kent to pledge. They receive the fraternity names "Pinto" (Larry) and "Flounder" (Kent). Vernon Wormer (John Vernon), dean of Faber College, wants to expel Delta from campus due to repeated conduct violations and low academic standing. Since they are already on probation, he puts the Deltas on something he calls "double secret probation" and orders the clean-cut, smug Omega president Greg Marmalard (James Daughton) to find a way to get rid of the Deltas permanently. Flounder is bullied by Omega member and ROTC cadet commander Doug Neidermeyer (Mark Metcalf), so Bluto and Daniel Simpson "D-Day" Day (Bruce McGill) persuade Flounder to sneak Neidermeyer's horse into Dean Wormer's office late at night. They give him a gun and tell him to shoot it. Unbeknownst to Flounder, the gun is loaded with blanks. Unable to bring himself to kill the horse, he fires into the air but the noise frightens the horse so much that it dies of a heart attack. In the cafeteria the next day, smooth-talking Eric "Otter" Stratton (Tim Matheson) tries to convince the stuck-up Mandy Pepperidge (Mary Louise Weller), with whom he'd had a one-time tryst, to abandon her boyfriend, the uninteresting Marmalard, and date him instead. Bluto provokes Marmalard with his impression of a popping zit by stuffing his mouth with a scoop of mashed potatoes and propelling it at Marmalard and table mates, Chip Diller (Kevin Bacon) and Barbara "Babs" Jansen (Martha Smith). Bluto starts a food fight that engulfs the cafeteria. Bluto and D-Day steal the answers to an upcoming psychology test, but it turns out the Omegas switch the discarded exam mimeograph stencil and the Deltas get every answer wrong. Their grade-point averages drop so low that Wormer needs only one more incident to revoke their charter and kick them out permanently. To cheer themselves up, the Deltas organize a toga party. They go shopping at the local market, using Pinto's thick cardigan sweater to hide loads of food they don't want to pay for. During the party Otis Day and the Knights perform "Shout". The dean's alcoholic, lecherous wife, Marion (Verna Bloom), attends the party at Otter's invitation and has sex with him. Pinto hooks up with Clorette (Sarah Holcomb), a girl he met at the supermarket, and makes out with her only to learn she is the mayor's 13-year-old daughter. He later takes her home in a shopping cart, abandoning her at the front door. Due to the party, Wormer organizes a kangaroo court with the Omegas and revokes Delta's charter and all their belongings are confiscated from their house. To take their minds off their troubles, Otter, Donald "Boon" Schoenstein (Peter Riegert), Flounder and Pinto go on a road trip in a car Flounder borrowed from his brother. Otter picks up some girls from Emily Dickinson College by pretending to be the fiancé of Fawn Liebowitz, a girl who recently died on campus. They stop at a roadhouse because Otis Day and the Knights are performing there, not realizing that it caters to an exclusively black clientele. The hulking patrons intimidate the guys and they flee, damaging Flounder's brother's car and leaving their frightened dates behind. Boon breaks up with his girlfriend Katy (Karen Allen) after discovering her sexual relationship with a professor (Donald Sutherland). Marmalard is told that his girlfriend is having an affair with Otter, so he and other Omegas lure him to a motel and beat him up. The Deltas' midterm grades are so poor that an ecstatic Wormer expels them all. He even notifies their draft boards of their eligibility. In the process, before Bluto attempts to speak to the dean, Wormer orders Flounder to speak, saying "Well? Out with it!", whereupon Flounder vomits on the dean. It seems time for the Deltas to give up, but Bluto, supported by the injured Otter, rouses them with an impassioned, historically inaccurate speech ("Was it over when the Germans bombed Pearl Harbor?!") and they decide to take revenge on Wormer and the Omegas. Stork shoves the drum major out from his position at the head of the marching band and leads them down a one-way alley, trapping them. Hoover attaches one end of a chain to a telephone pole and the back of one of the floats, tearing it apart. Several other Deltas use a makeshift mortar to launch flares onto the street. When Neidermeyer and his ROTC unit chase after the Deltas, Flounder tosses a large jar of marbles in their path, spilling them all to the pavement. Flounder produces a large soda sprayer for Neidermeyer but he's forced to retreat when Neidermeyer loads his marching rifle with a live round, shooting out the soda bottle. Chip Diller, who gradually becomes hysterical, tries to calm the fleeing crowd and is trampled. To top it all off, the Deltas have converted Flounder's brother's Lincoln into a parade float with the words "EAT ME" sculpted on the sides. They cut the flowered portion away to reveal the work they did to make the car demonic -- the "DEATHMOBILE" -- complete with a turret and train whistle, and ram it into the spectator's bleachers, upsetting the Dean, his wife, the mayor and their guests. Hoover approaches the Dean and asks for one more chance. Finally, the futures of many of the main characters are revealed. The last shot of the film is of Bluto driving away in a white convertible with his soon-to-be wife, Mandy Pepperidge.