At the beginning of this episode, we see a fierce wolf scaring some guard dogs before breaking into a house. The scene then cuts to one of Muldoon and Kirby discussing a news report of a "wolf burglar", while the Rescue Rangers listen from on top of the police car. Dale thinks the creature is a werewolf, like in the comic book he is reading, but Chip doesn't believe it and tells Dale to be quiet.
Just then, however, a report of a wolf robbing a house comes over on the police radio. At the house in question, a man says the wolf is upstairs and Muldoon and Kirby go to investigate, closely followed by the Rangers. The wolf escapes through an open window, leaving behind a tuft of fur. Chip retrieves the fur, telling Dale that he will prove there is no such things as werewolves.
Later, Gadget confirms that the fur did come from a wolf but says it is just an ordinary wolf, not a werewolf. Dale comes in lugging an armful of wolfsbane, which, he claims, deters werewolves. Chip, however, retorts that this only works in comics.
At the zoo, the Rangers question a wolf named Harriet, who tells them that her mate, Harry, has somehow been escaping from their cage, only to return the next morning. Harry claims not to remember anything so the Rangers spend the night with the wolves, hoping to find out how he is getting loose. It turns out that they don't have long to wait before Harry turns into a "human" and climbs the fence.
Later, the Rangers catch up with Harry in a clothes shop, where he is "picking up some decent threads"; to complete his outfit, he takes the wolfsbane Dale has been carrying around and turns it into a buttonhole. He then goes to a restaurant and sits "wolfing down" several chicken legs, before being thrown out for not being able to pay his bill. Chip tries to persuade Harry to go back to the zoo, but he refuses and hops into a nearby car as the Rangers jump in after him. Ignoring Gadget's warning not to, Harry then takes the car for a joyride.
Later, the Rangers catch a glimpse of the "wolf burglar" just as he changes into a man; seeing this, Dale is more convinced than ever that there is a werewolf on the loose. At the same instant, Harry turns back into a wolf and crashes the car he stole. Luckily, none of the animals are hurt, but Muldoon and Kirby have been chasing the "wolf burglar" and capture Harry, thinking he is the wolf they are after.
Chip tells Monty, Gadget and Zipper to go to the animal shelter and rescue Harry. Meanwhile, he and Dale will track down the "werewolf". He finds a trail of wolf's pawprints leading to Professor Nimnul's lab and the two chipmunks head there to investigate.
At the lab, Chip and Dale learn that Nimnul is the one behind the burglaries. He has invented a device called a Metamorphosizer, which, when placed on two different animals, can be used to cause them to take on each other's physical characteristics. Chip and Dale remove two such devices from a rabbit and a Tasmanian devil, but, as they prepare to leave, Nimnul spots them.
Nimnul chases after the chipmunks and, realising he is never going to catch them in his human form, changes into a "wolf", just as the other Rangers set Harry free. Chip and Dale are hard pushed to shake him off and are soon cornered by a shelving unit. Chip, seeing that the shelving unit is somewhat unsteady, gives it a little nudge with his paw and causes a flask to fall on Nimnul's head.
Nimnul pulls the flask off his head, but, while doing so, he sends himself flying and the Metamorphosizer he is wearing gets broken. Chip and Dale then lure him into the Tasmanian devil's cage, delaying him long enough for them to make their escape. Back at the zoo, they tell the others what they have found out.
Since Nimnul's Metamorphosizer is broken, it appears Harry is stuck as a "human". Luckily, Gadget manages to reset one of the Metamorphosizers Chip and Dale retrieved; the Rangers plan to place it on Nimnul so that he and Harry can turn back into their usual forms. But a sudden jolt from the device startles Gadget and Dale, catching her, accidentally sends the other Metamorphosizer rolling out of the cage.
Nimnul bursts in and orders the Rangers to return the Metamorphosizer. Chip and Dale immediately hand it over, but, instead of turning back into a human, Nimnul becomes a cross between a human, a wolf and a crocodile; this is because the other Metamorphosizer has landed on a crocodile's nose. Harry is still in his "human" form, but the crocodile gets transformed as well, seconds before an ostrich gets hold of the device.
As Nimnul acquires an ostrich's body, Chip tells Zipper to get the other Metamorphosizer. Zipper flies off as Muldoon and Kirby arrive at the zoo to investigate a report of "monsters". The two police officers see Nimnul (who, by now, has human, crocodile, ostrich, wolf and elephant characteristics) and trap him in a net. Zipper retrieves the Metamorphosizer, but not before all the animals in the zoo have been affected by it.
Later, Gadget uses the Metamorphosizer to restore all the animals (including Harry) to normal. Chip tells Dale that he (Chip) was right all along about there being no werewolf, to which Dale replies that he has had enough of werewolf comics anyway.