Dr. Hendrickson is a high-ranking employee at Sterling Labs. He is assigned to work with Wayne Szalinski, inventor of the shrinking machine to develop a new machine that makes objects grow in size. However, Hendrickson insists on doing everything his way, and refuses to listen to Wayne's ideas. Hendrickson has also arranged with the lab's security personnel to bar Wayne from accessing the lab's equipment without his permission.
On a Saturday, during his day off, Hendrickson is playing tennis when he receives a call from the security guard at the lab informing him that Wayne Szalinski was at the lab trying to work on the machine without his permission. By the time Hendrickson gets there, Wayne has already left, but Hendrickson finds that Wayne's experiments caused a power surge which damaged the equipment. Unbeknownst to Hendrickson, Wayne had gotten the machine to work when he accidentally zapped his two-year-old son Adam with the machine's ray. At first, it looked like nothing had happened, but whenever Adam came into contact with electrical appliance it caused him to grow.
Wayne goes back to the lab to try and shrink Adam back to normal size, but is instead confronted by Hendrickson, who informs Wayne that he is off the project. Wayne reminds Hendrickson that he does not have the authority to make that decision, that honor goes to Dr. Clifford Sterling, the CEO of the lab, but Hendrickson informs Wayne that Sterling will not want to listen to him after the damage he caused. Wayne does not tell Hendrickson that he managed to get the machine to work as he does not want to subject Adam to numerous observations and tests (he explains that the very large, gibberish-speaking person who accompanied him to the lab was a relative visiting from Yugoslavia).
After Wayne leaves, Hendrickson instructs a couple of the lab technicians to try and find out what Wayne was up to. After they uncover a bizzare image of Adam Szalinski and his stuffed bunny, Hendrickson decides to pay Wayne a visit.
Hendrickson makes his way to the Szalinskis' house only to find a 14-foot-tall Adam playing in the street, surrounded by bystanders. Adam has caused a lot of damage, and Hendrickson arranges for Adam to be taken away in a large tractor-trailer. Hendrickson's plan is to have Adam, whom he believes to be mutated, to be taken back to the lab to undergo testing (much to Wayne's outrage). However, the truck passes by high-voltage power lines causing Adam to grow even bigger, he bursts out of the truck, knocking it over, and proceeds to pick up his brother Nick and babysitter Mandy and put them in his pocket before heading toward Las Vegas.
Hendrickson summons Dr. Sterling to the scene. When Sterling arrives, Wayne pleads with him to give him a chance, promising to return his son to normal size. Hendrickson proceeds to mock Wayne, prompting Wayne to deliver an empassioned speech about inventors. Dr. Sterling realizes that Wayne isn't the fool whom Hendrickson made him out to be, and tells Hendrickson that he is fired, which Hendrickson refuses to accept.
Hendrickson vows to subdue the overgrown Adam his own way. He rents a military helicopter and a tranquilizer gun. The captain of the helicopter is reluctant to go along with this plan, but Hendrickson produces the required paperwork for the operation, and takes off in the helicopter. By this point, Adam has grown so large that he towers over the city of Las Vagas and terrorizing the people. He has picked up the Hard Rock Cafe guitar and, thinking it's a real instument, is trying to play it. Hendrickson aims the gun at Adam, but just as he fires the captain makes a sudden maneuver causing him to miss. Hendrickson tells the captain that he to make sure this will be the last mission the captain flies if he makes him miss again, and shoots a second tranquilizer dart at Adam; it misses and hits the guitar instead, causing Adam to drop it and start crying. Hendrickson aims again, but just then an over-size Diane Szalinski, whom Wayne had enlarged using his original machine, grabs hold of the helicopter and tells them to back off. She them places the helicopter on the ground, causing it to explode, and manages to subdue Adam. Adam and Diane are then returned to normal size with the shrink ray.
Once back on the ground, Hendrickson reluctantly congratulates Wayne on returning his son to normal size. Diane then confronts Hendrickson about trying to shoot Adam, but Hendrickson assures Diane that the tranquilizers would not have hurt him. Diane then punches Hendrickson hard in the face, knocking him out. Dr. Sterling calls for an ambulence but remains firm on his decision to fire Hendrickson, jokingly remarking that Hendrickson is "overcome with the prospect of having to find a new career."