Muriel is tending to her garden when an innocent rabbit approaches hungrily. Muriel reaches for a carrot to feed the rabbit, both unbeknownst to some creature burrowing through the soil rapidly towards them. The creature, a large, furry beast with sharp teeth, bursts from the soil and snatches the rabbit, dragging it into the ground, making a likely meal of it. Muriel turns back to the ground to see the rabbit missing. She reaches into the hole with the carrot only to be bitten on the hand by the beast.
Courage and Eustace take Muriel to Dr. Vindaloo, who claims there is nothing Muriel or himself can do, just to "keep soaking it." They return home where a full moon causes Muriel to become disoriented and feel ill. Courage walks into the kitchen to discover Muriel has transformed into a ferocious creature with sharp teeth, similar to the animal that bit her. Courage brings Dr. Vindaloo to the house where Muriel attacks the doctor and disappears under the house. Eustace encounters the beast-transformed Muriel and afterwards, Muriel attacks Dr. Vindaloo again and drags him under the house.
Eustace claims it's just a mouse and goes to retrieve his mallet. Courage realizes Eustace is no help and tries to find some information on the computer. The computer tells Courage that Muriel has been bitten by a weremole and the only way to cure Muriel is to retrieve a hair from the mole that bit her. Courage dons a rabbit suit and lures the weremole that bit Muriel into attacking him. Meanwhile, Muriel attacks Eustace where he attempts to fend her off with a mallet. Courage manages to retrieve a hair from the mole and rushes upstairs to save Eustace as he is cornered by Muriel. Courage drops the hair into Muriel's mouth where she chokes and falls through the floor. The plan seemingly has worked. Eustace and Courage go downstairs to see a normal Muriel sitting in her chair. When it seems everything has gone back to normal, Dr. Vindaloo—who has also transformed into a weremole—bursts from the floor and attacks Eustace. Eustace tried to attack back with his mallet (got 6 hits) but he eventually got eaten and the episode ends with Courage saying"Is there a doctor in the house?!"