Each episode shows Stanley (voiced by Jessica D. Stone) in a situation he does not fully understand. He discusses it with his pet goldfish Dennis (Charles Shaughnessy) before consulting the Great Big Book of Everything, a remarkably complete zoology book aimed at young children or his computer. By observing how an animal copes with the same situation Stanley faces, or how it can overcome a similar difficulty, Stanley learns to deal with the situation himself.
Throughout the show Stanley and all his preschool aged friends are able to talk to his pet cat, Elsie (Hynden Walch) and dog Harry (Rene Mujica) as well as Dennis. Other animals also seem to occasionally respond, but never talk or give a definite indication they truly understood what was said. Stanley and his friends actively try to keep the adults (that is, except Stanley’s grandmother), and by extension Stanley’s older brother Lionel, from realizing this.
The Great Big Book of Everything appears to be magical in nature, able to either let the animals out of the pages or allow the children to enter, sometimes changing them into animals in the process. This does not appear to be imaginary since occasionally adults do notice the noise, and Stanley works hard to hide the animals. There is also an episode where Stanley’s brother sees a T-Rex in the yard but dismisses the memory when it disappears back into the book…