Meanwhile, a sadistic veterinarian, Dr. Herman Varnick (Dean Jones) involved with animal experimentation is planning to kill Beethoven for his latest experiment, and George, after discovering his fondness for the dog, springs into action to rescue his pet.
While George and his family are in Europe, Beethoven is riding with the relatives of the Newtons led by George's brother Richard (Judge Reinhold) as the family avoids criminals that are after a DVD copy of The Shakiest Gun in the West that has a computer code hidden in it.
Beethoven tries to find a way to get home, while a butler who works for Sedgewick family wants to kidnap Michelangelo for ransom.
Sara takes Beethoven to visit her oddball uncle in the old mining town Quicksilver, where they discover the hidden treasure while also facing two bank robbers who want it too.
In Beethoven's Christmas Adventure, Beethoven teams up with the elf from the North Pole named Henry (Kyle Massey) and a young boy Mason Cooper (Munro Chambers) to find a missing Santa's toy bag that fell in the small town Wood Haven, Minnesota, while also facing two men from a toy store, Sylvester Smirch (Robert Picardo) and his assistant Kenny (Curtis Armstrong), who grab Santa's bag and use it for financial gains.
They become stranded in a small coastal town, where the beloved canine befriends a young boy who is searching for buried treasure.