While their parents are away on business in Atlanta, Gretchen and Clark have to stay with their grandparents in Mud Town. Bo-ring! Grandma Rose and Grandpa Eddie are really forgetful—so forgetful that they've gone out for the day and forgotten to warn them that there's a monster locked upstairs!
- Courtney Hawkrigg as Gretchen
- Ricky Mabe as Clark
- Helen Hughes as Grandma Rose
- Peter Boretski as Grandpa Eddie
- Tim Rykert as Swamp Monster
Differences from the Book
- The Swamp Monster has a different appearance than its description in the book.
- Their dog, Charley, does not appear.
- Gretchen and Clark put the ingredients into a gumbo, while in the book it was a pie.They also grab more ingredients from the cupboards.
- In the television episode, Gretchen concludes that the monster is allergic to humans when Clark thrusts his arm into the monster's mouth, which causes the monster to explode. In the book, the monster licks Gretchen's arm, and it growls that it's allergic to humans before dying.
- In the book, Gretchen and Clark became step siblings years prior to the events of the story. In the episode, Grechen's Dad and Clark's Mom got married just before the events of the episode.
- Rose and Eddie only write one letter, and the message about the monster is on the back instead of being the main point of the letter.
- In the book, the monster invaded Rose and Eddie's home. In the episode, Eddie shot the monster while hunting and brought it home, assuming it was dead.
- This is the third of four television episodes on the Monster Blood DVD.