Becoming more and more involved with the Bentley Circus, in spite of their determination to stay out of other people's troubles, Hop and Tank unwittingly made an enemy of Chuck, the circus stunt pilot, when they reprimanded him for flying too low over the town of Lakeville. Following that, they discovered that Bongo, the huge and ferocious Gorilla they had helped recapture, had not escaped from his cage accidentally - someone had tampered with the lock!