Few people know of the existence of pirats, but they have been around as long as there have been pirates sailing the high seas. These rats are exactly what their name implies. They help the oblivious humans run their ship and secure their treasure, all without revealing their presence. However, the mice twins Albert and Adelaide are all too aware of the pirats' existence. When their ship is attacked by a fearsome pirate vessel, the Manta Ray, Albert and Addie are taken hostage by Captain Waverider and his crew. Although the pirats certainly cut an intimidating figure, the twins soon discover that there is more to them than meets the eye. Waverider and the others are growing weary of the pirate life but don't know how to quit it. They enjoy showing the twins the fruits of their labor and praise Albert when he comes up with ingenious mechanical solutions to their problems. The usually fearless Addie, on the other hand, must reckon with fear and anxiety for the first time in her young life. When the pirats' biggest enemies kidnap Addie, Albert will have to summon his courage to save not only his sister but also the entire ship!