When Sara takes Beethoven to spend summer vacation with wacky Uncle Freddie in an old mining town, the mischievous canine "digs up" the missing clue to a legendary hidden fortune of Rita and Moe Selig. Now everybody wants to be the dog's best friend as his discovery unleashes a frenzy of treasure hunting among the community's cast of kooky creatures. With help from Uncle Freddie and Garrett (a friend or maybe more), Sara and Beethoven try to help uncover a secret that has been in the crazy little town for years.

After being implanted with a microchip that gives him special powers, a dog engages a young boy in conversation and adventure. Befriended by a local police officer, the dog, the boy and his friend go on a quest to save the world by undoing the insidious plot of an evil scientist to turn all kids into mindless robots.