Jack and Nickels are two mean and cruel cats who will eat just about anything with meat. Despite being good pets to their mistress, Mrs. Sweeney, they admit that they are fed up with eating birds, which she keeps feeding them, and are somewhat fed up with her ways of cuddling them like little kitties. They will do anything to get their hands on something else with meat; namely mice and other types of rodents (like chipmunks), thus, making them more carnivorous. They don't like it when their mistress loses her birds when already it's their duty to guard them.
Jack and Nickels are first seen sleeping in their mistress', Mrs. Sweeney, bakery factory while guarding the birds she kept on stealing using a powerful magnet. Then, they wake up when Nickels hears a sound but Jack concludes it's just their mistress coming to feed them some more birds. Nickels admits he is sick and tired of eating birds and Jack says he would do anything (like give up his claws) for a nice mouse snack or any other rodents they can find.
Jack and Nickels' prayers are answered when they spot Chip and Dale sneaking in their factory. The cats chase the chipmunks all the way until they make the chipmunks run close to an oven where the cats are waiting for them at the end of the line. But before any further misfortune befalls Chip and Dale, Mrs. Sweeney and her son, Todd arrive and the cats decide to deal with them later. Out of annoyance and regret, they cuddle their mistress.
A few moments later, they hear another sound and when they notice the chipmunks and their friends: Gadget, Monterey Jack, and Zipper sabotaging their mistress' machine and freeing the birds, they screech in fear and comment about Mrs. Sweeney's reaction when she finds out about all this.
Then, Jack and Nickels give chase to Dale and Monterey Jack until they are defeated by them; thanks to a few mirror tricks.
Finally, with the Rescue Rangers using the magnet, Jack and Nickels along with Mrs. Sweeney and her son are attracted to it thanks to the metal collars they wear. Then, they are all arrested by the sheriff and taken to jail.
- Jack and Nickels' names were derived from the actor Jack Nicholson.
- It also made references on how he portrayed unique and challenging roles, many of which include dark portrayals of excitable, neurotic, and psychopathic characters.
- As Chip and Dale are getting closer to the oven, Jack says, "Heeeere's dinner!" This is a reference to Jack Torrance's (in)famous line "Heeeere's Johnny!" featured in The Shining.