Trim is eager to do a good job on his first day as ship's cat--but what is his job? All around him, members of the crew are busy with their responsibilities--too busy to notice a small kitten looking for an opportunity to contribute. Jack the parrot directs Trim to the hold, to patrol for rats. But Jack neglects to tell Trim exactly what a rat is. Surely Princess Bea, the new friend he meets below deck, isn't a rat. She doesn't resemble the creepy, scary-looking creature that Jack warned Trim about and she's happy to have an assistant to fetch her biscuits from the galley.