A slobbering St. Bernard becomes the center of attention for a loving family, but must contend with a dog-napping veterinarian and his henchmen.

Beethoven, the St. Bernard dog, becomes a father, but his girlfriend Missy is dognapped, and his puppies are in danger of the same fate.

The Newton family from the first two Beethoven movies is on vacation in Europe, but they do plan to attend a Newton family reunion, and to make sure one of their family members definitely makes it, they ship him to travel to there with George's brother, Richard. Guess which one it was? That's right, Beethoven. He follows Richard and his family as they hit the road to California in a huge, shiny, and expensive RV, equipped with a DVD player. Following them are two bumbling crooks who have hidden some secret codes on a DVD that they figure no one in the world will buy, but someone does: Richard. So now they have a DVD holding top secret information, and the crooks must get it back.

The family is pleasantly surprised and puzzled when Beethoven suddenly becomes obedient. Turns out it's a prince and the pauper scenario, with the real Beethoven now living with a pompous rich family.

Sara Newton and Beethoven spends summer with Freddy Kablinski in Quicksilver, a weird town.