April Fools' Day is not a happy one for Wagner the mouse because his best friend, Pearl the rabbit, and other children and adults at school keep tricking him.
Pearl and Wagner, a rabbit and a mouse who are best friends, learn about secrets during a trip to an ice cream factory and an amusement park birthday party.
Rhino's impetuosity and housemate Mouse's meticulousness clash in comic fashion as the friends celebrate a holiday, get Rhino out of a tight spot, and dress up as each other for a costume party.