Corneil is an intelligent dog: not only can he read and write perfect English, but he is much smarter than most people. Since he's so smart, he knows that life doesn't get any better than being a pampered pet, and so he does anything he can to keep his owners from realizing his phenomenal skills. This plan begins to go awry when his owners hire the pinheaded Bernie Barges to "dog-sit", and Bernie learns about Corneil's secret. Though the two frequently bicker, they form an uneasy friendship, and Corneil finds himself using his brainy powers to bail Bernie out of various scrapes.
Most episodes are driven by Corneil's reluctance to let anyone know that he is intelligent and capable of human speech. The only person who does know is dogsitter Bernie, whose uncle minds the apartment of Corneil's wealthy owners. Bernie found out about Corneil's speaking abilities by accident, and unfortunately he is somewhat lacking in intelligence and mostly devoid of morals. All this puts Corneil in an uncomfortable position - as Bernie often takes it upon himself to 'be the voice' of Corneil, capitalising on Corneil's reluctance to communicate and ignoring Corneil's requests.