After Harold comes home from surgery, Chester and Bunnicula commit to helping their friend get some rest and read him a bedtime story. But after a monstrous hybrid of a spider and a lamb emerges from the book, they're afraid their immobilized friend will be eaten! Bunnicula and Chester team up to save their friend.
Harold comes home from the vet after eating a soccer ball and asks Chester and Bunnicula to read him a bedtime story. They read him a story about the SpiderLamb from the Evil Book, but the SpiderLamb emerges and chases Bunnicula and Chester out of the room.
Chester and Bunnicula reenter the room armed with household objects, despite Bunnicula's insistence that reading more of the book will cause it to absorb the SpiderLamb. Bunnicula attacks the SpiderLamb while Chester attempts to save a sleeping Harold. However, the SpiderLamb creates sticky clothes out of webbing on their bodies, and after a while, they are forced to retreat.
Chester has Bunnicula eat a squash, causing him to grow a huge foot. Chester tries to get him to step on the SpiderLamb with the foot, but the creature just shoots webs at it, causing Bunnicula to get stuck. After a while, Chester and Bunnicula flee the room again.
Chester finally agrees to keep reading the book. When they reenter the room, the SpiderLamb has laid eggs on Harold. Bunnicula keeps the creature distracted with magic tricks while Chester reads from the book, causing the SpiderLamb to grow into a more demonic form. The SpiderLamb begins to attack Chester as its eggs hatch, but the eggs hatch at the end of the story in the book, meaning the story is over. This causes the SpiderLamb to get sucked back into the book. Harold finally wakes up, completely oblivious to everything that happened. However, the baby SpiderLambs turn out to still exist in the real world.
- It is the first episode where Harold is not a main character.