Two thieves, Harvey and Vernon, steal a group of puppies from a pet store. A
St. Bernard puppy escapes and sneaks into the home of the Newton family. The patriarch, George, is a
control freak and
workaholic who does not want a dog. However, his wife, Alice, and their three children, Ryce, Ted, and Emily, convince him to take the dog in. The dog is named "Beethoven" after Emily plays a portion of
Ludwig van Beethoven's
Fifth Symphony on the piano and he barks along to it. Beethoven quickly grows into a large dog, and George must clean up after the lovable, but slobbery, mischievous animal. Beethoven becomes an important part of the family: he helps Ryce talk to her crush Mark, scares off some bullies harming Ted, and saves Emily's life when she falls into an irresponsible babysitter's swimming pool. George still maintains his dislike, which is further aggravated when the dog's antics ruin a barbecue he is hosting for Brad and Brie Wilson, unpleasant
venture capitalists looking to invest in and, unbeknownst to George, swindle him out of his car
air freshener firm. The Newtons take Beethoven to veterinarian Dr. Herman Varnick for a routine medical exam, unaware that he is secretly involved in unethical animal experiments and is seeking large-skulled dogs to test ammunition on. Dr. Varnick tells George of a supposed mental instability among St. Bernards that makes them potentially dangerous and violent, advising him to watch Beethoven closely for any sign of viciousness. Later, under the pretense of doing a follow-up exam on Beethoven, Dr. Varnick visits the Newton home. After applying fake blood onto his arm and Beethoven's nose, Dr. Varnick repeatedly hits Beethoven until the dog retaliates, unaware that Emily saw him. When the rest of the family comes outside to rescue Dr. Varnick, he claims that Beethoven attacked him without provocation and must be
euthanized. Dr. Varnick also threatens to press charges if the Newtons refuse. Despite Emily's protests that Dr. Varnick is lying, George reluctantly takes Beethoven to Dr. Varnick's office. On the way there, George remembers that his own father took the family dog to be put down at the vet, something that George never forgave him for. George fears that his family will similarly hate him; when George returns home, his fears are realized when Alice and the kids refuse to eat dinner with him. Alice convinces George that they should believe Emily rather than someone they only met twice. The Newtons all return to Dr. Varnick's office to reclaim Beethoven, but Dr. Varnick says Beethoven already passed away. George remembers that the receptionist told him that Beethoven would not be put to sleep until the next morning before noticing that Dr. Varnick has no bite marks on his arm. Realizing that Emily was telling the truth the whole time, George punches Dr. Varnick square in the face and leaves. Afterwards, the Newtons covertly follow Dr. Varnick to his warehouse, where Beethoven has been kept the whole time. Beethoven manages to escape from his cage but is recaptured by Harvey and Vernon, who are working for Dr. Varnick. As Alice tries to call the police, George goes to the top of the building to spy through the skylight. The skylight shatters, and George falls to the ground in front of Dr. Varnick, who prepares to shoot both him and Beethoven. However, Sparky, a captive
Jack Russell Terrier that Beethoven had earlier befriended, bites Dr. Varnick in the groin, causing him to fire a shot into the air. Ted hears the gunshot and smashes the car through the warehouse entrance, crashing into a cart and launching numerous syringes into Dr. Varnick, sedating him. As the Newtons reunite with Beethoven and free all the captive dogs, they notice Harvey and Vernon trying to escape. Ted sends the dogs after them, but Harvey and Vernon escape into a junkyard, only to be attacked by several
Doberman guard dogs. Dr. Varnick, Harvey, and Vernon are all arrested for animal cruelty. The Newtons are praised as heroes in the news, George takes a new liking to Beethoven, and Ryce gets a call from Mark. The Newtons then go to sleep, saying good night to Beethoven and all the other dogs they rescued. ==Cast==