Sylvester Cat accepts a position as mouse-catcher on a ship, and his son, Junior, accompanies him. They encounter baby kangaroo Hippety Hopper being shipped from Australia and, as usual, mistake Hippety for a giant mouse.
Cats A-Weigh!
Sylvester and Junior become ship cats to hunt mice. Sylvester tells Junior to get the small ones and he'll get the bigger ones. Hippety Hopper gets loose and it looks like it's up to Sylvester to catch the big mouse.
