For Halloween, Uncle Grandpa throws a haunted house in the RV, a couple of teenagers decide to go first in the RV since every other haunted house didn't scare them. Once they see that Uncle Grandpa's haunted RV isn't scary, Uncle Grandpa improves the haunted RV by putting Frankenstein's brain under the hood of the RV, and it turns the whole RV into a haunted house filled with monsters and the haunted house keeps the teenagers captive, so Uncle Grandpa and friends must go in and save the trapped teenagers.