Snoopy is lying on top of his doghouse when he hears music. He follows the music and finds a circus unloading. Among other animals, he sees three poodles, and immediately latches onto the white one (whom the audience later learns is named Fifi). He follows her to the entrance of the big top with his tongue hanging out and his pupils shaped like hearts, then stops. Polly, the dog's trainer, sees Snoopy and pulls him inside.

The next day, Peppermint Patty calls Charlie Brown to tell him her school gave all students the day off to see the circus. Charlie Brown tells her that his school will be closed as well, and they decide to attend the circus together. At the circus the children see Snoopy perform as part of a dog act. They all realize it is Snoopy and eventually relish in his new "career", despite Snoopy's shortcomings being completely untrained. However, Charlie Brown isn't having any of it, exclaiming Snoopy's career is being his dog.