Russ is hot-tempered and easily angered. He is constantly at war with his next-door neighbor, Wayne Szalinski, due to Wayne's inventions making loud noises that disturb him. He also is having trouble bonding with his oldest son, Russ Jr., as he wishes for him to be just like his father, and is frustrated with his rebelliousness. He also struggles with his addiction to tobacco. He told his family he quit; although in a stressful situation he relapses.
Despite these issues, Russ deeply cares about his family and will do anything to keep them safe.
Role in the film
Russ is awakened by loud noises coming from Wayne's house. He is preparing to leave on a fishing trip with his family and needs his sleep, as they have a four-hour drive ahead of them. He opens the window and yells at Wayne to knock it off. Mae sleepily tells him that what Wayne is doing involves construction, and he should understand this as he works in that. He ignores this and instead goes outside to yell at Wayne some more. When he goes to his backyard, he encounters his younger son, Ron, who was camping out in there in preparation for the trip. Russ accidentally sets off a booby trap set by Ron and is shot in the head by a toy arrow with superglue on the tip, and he and Mae go back inside to wash it off before it dries.
Back inside, Russ asks Russ Jr. if he's ready for the trip. He says that fishing is not his thing, and slams the door in his face. Mae then informs him that Russ Jr. had been cut from the football team the previous day, and the last thing he needs is to be confronted by Russ. He doesn't understand this and informs her that when he was Russ Jr.'s age he was captain of the football team, and if his father had wanted him to go on a fishing trip he would have been grateful.
Throughout the day Russ observes that while Ron is eagerly looking forward to the trip, Russ Jr. wants nothing to do with it. He wishes that Russ Jr. could be more like Ron, but Mae tells him to give him a chance. He tries to get Russ Jr. to lift weights in order to build up his strength for the football team. When Russ Jr. continues to give him a hard time he gets angry and yells at him. After this incident, he goes outside and starts to light a cigarette. But Mae catches him.
Unbeknownst to Russ, Ron, who was playing baseball in the backyard to pass the time, accidentally hits the ball into the Szalinskis' attic window. Russ Jr. sees this and forces Ron to go to their house with him to explain what happened. When they go up to the attic to retrieve the ball, they are shrunk by Wayne's shrinking machine, which had been activated by it.
Some time passes and Russ and Mae notice that Russ Jr. and Ron are missing. Mae asks Wayne's wife, Diane, if she had seen them, and she says that their kids, Amy and Nick, are missing as well. This greatly worries Russ.
When the Forresters (friends of the Thompsons who were to go on the trip with them) arrive, Russ informs them that they can't go and lies by explaining that Mae isn't feeling well. After they leave, he angrily declares that Russ Jr. and Ron have made them waste their $80 deposit, and will be grounded once they're found.
Some more time passes and Mae decides to call the police to report Russ Jr. and Ron missing. When they arrive, Russ is further angered when one of them tries to imply that Russ Jr. and Ron may have run away as a result of an argument with their parents. It is then that Mae reveals to Russ that Russ Jr. had not been cut from the football team after all, but had quit it instead, and was afraid of how Russ would react.
A deeply worried Russ goes outside to light a cigarette. While smoking it, he observes Wayne and Diane behaving very oddly. They are tied to harnesses suspended from a cable wearing helmets with lights on them, and calling their kids' names while peering into the grass. Russ tosses his cigarette into their yard.
A while later, Wayne and Diane overhear Russ and Mae arguing loudly, and decide to tell them the truth about what happened to Russ Jr. and Ron. Upon being informed that the machine shrunk them, Russ explodes and tells Wayne that he's the one who needs a shrink, as Russ believes he's crazy.
Eventually, the kids are found, and Diane informs Russ and Mae, who come back to the Szalinskis' attic to watch them be returned to normal size. However, Wayne has trouble figuring out what caused the machine to work, as prior to all this, it had been blowing things up. The kids are able to demonstrate that it was Ron's baseball that made it work; it had been producing too much heat causing things to blow up, but the ball came through the window, activated it, and had gotten in the path of its laser, reducing its intensity. Wayne manages to find the ball, but Russ tells him that he must test the machine before the kids are returned to normal size. Wayne volunteers to have them do so on him, but Russ bravely insists that it be him instead. It works and Russ is shrunk, then returned to normal size (or almost, as his cap, which he had taken off prior to being shrunk, is now a bit too large).
The kids are then returned to normal size. Ron tells Russ that he didn't mean to ruin their day, as he had wanted to go fishing. Russ Jr. says that he will rejoin the football team if Russ really insists on it, but Russ says that he will no longer insist that he follow in his footsteps anymore, and can do what he wants.
Russ then decides to reconcile with Wayne, and they shake hands. The film ends with the Thompsons and Szalinskis having Thanksgiving dinner together, with the food having been enlarged to enormous portions.