Plot
Eddie Thornton, a struggling animal trainer and widowed father, is an assistant animal trainer to Sal DeMarco, an untalented, egocentric animal show host. Both men have been hired to train the animals for a film called Frizzy, The Bichon Frise: Sal as the dog handler, and Eddie is given only the responsibility of training the lizard. When Frizzy is kidnapped, Sal blames Eddie for being responsible for the dog handling. Eddie is promptly fired by the severe producer Patricia. The director Stanley and Patricia refuse to pay the ransom and they decide to instead hold auditions for the new Frizzy.
Meanwhile, Eddie's son, Billy, is walking around town when he discovers a large, stray dog is following him. Billy then brings the dog home and names him Beethoven when the dog shows interest in Ludwig van Beethoven's 5th symphony, after initially trying to call him Wolfgang. Eddie comes home to discover that, not only is his job gone, but now his house is wrecked by an oversized dog adopted by his son.
It transpires that the one responsible for Frizzy's disappearance is Sal, accompanied by his two other cronies Tick and Bones. He admonishes them for not waiting until Frizzy had already shot some of the film, in order to make her valuable.
The next day, when auditions are held, Stanley and Patricia have difficulties finding the right dog to replace Frizzy. Eddie has arrived (with Billy and Beethoven in-tow) to pick up his lizard, Pete. Suddenly, Beethoven bursts in and performs an impressive chase scene with Pete the Lizard, which instantly makes Stanley love him. Beethoven and Eddie are hired on the spot and Sal is fired by Stanley.
To celebrate, Eddie takes Billy and Beethoven out for hamburgers, but Beethoven escapes with the burgers and leads Eddie and Billy on a chase. Finally, they find where Beethoven was going: he had been caring for his three small pups in an alley, as their mother had apparently died. Eddie begrudgingly adopts the puppies, as well.
Eddie is then charged with having Beethoven perform the requested stunts in the film, but Beethoven proves to be "untrainable", and instead, often crashes through the scene and making a sloppy mess in the process. Each time, Eddie is prepared to be fired, but Stanley finds these scenes even funnier and orders the scenes printed for the film. Lisa, the film's writer, requests from Eddie to spend more time with Beethoven so that she can write more appropriately for him.
As revenge for being fired from the studio, Sal orders his henchmen to kidnap Beethoven for the million-dollar ransom, planning to kill him after the ransom is paid. They kidnap him while Billy is flirting with his crush Katie in the park. Eddie, Billy, Lisa and the puppies then head to Sal's show stage, which doubles as his secret lair, and rescue Beethoven. Sal and his goons are arrested, and Eddie and Lisa begin a relationship.
The film ends with Eddie, Lisa, Billy, Katie, Stanley, Patricia, Beethoven, the pups, Frizzy and Pete the iguana, all enjoying popcorn while watching the film's premiere.
The end credits have film title parodies. These include "Dog-E", "When Hairy Met Frizzy" and "The Lizard of Oz". During the Gag Reel, Jonathan Silverman refers to Sal DeMarco as "Ned Ryerson". This is because the actor who played Sal, Stephen Tobolowsky, portrayed the character Ned Ryerson in the Bill Murray comedy, Groundhog Day .
