Sylvester takes his son Junior to an old, broken-down, mouse-infested mansion near some railroad tracks to prove his mouse-catching ability. Baby kangaroo Hippety Hopper falls out of a passing circus train and turns up in the house. “He’s only a mouse, Father, and cats aren’t afraid of mice,” Junior helpfully points out. Sylvester and Junior, as usual, mistake him for a giant mouse, and Sylvester is obliged to fight the playful Hippety.
