A man named Fergus signs Timon and Pumbaa up to stay at a castle in Ireland in order for the duo to receive a leprechaun's treasure. Fergus' cousin Keegan tells Timon and Pumbaa that the castle is haunted, but Timon doesn't believe in ghosts.
Timon and Pumbaa arrive at the castle and as they get inside, someone pushes down a rock to the two friends. Pumbaa gets frightened as the rock breaks, thinking that it might be a ghost that pushed it. When Timon and Pumbaa get inside, Timon asks Pumbaa to get some light since he can barely see anything in the castle. When Pumbaa gets a candle, a man in a picture lights it out. Pumbaa sees this and runs to Timon in fear and hides under a carpet, telling his friend that the ghost blew out the fire. Meanwhile, in another part of the castle, a green ghost overhears Timon and Pumbaa and is happy to have visitors, stating that he has been waiting for company for 200 years.
Timon, still refusing to believe in ghosts, drags Pumbaa up the staircase. Suddenly, what looks like a person in a ghost costume grabs the rug off the stairs and makes Timon and Pumbaa slide back down, with Timon now realizing that Pumbaa was right about the castle being haunted. The green ghost sees the person haunting the two friends and decides to do something about it.
Timon and Pumbaa run to the door, trying to open it. The green ghost passes through the door and tries to prevent the person from scaring away the duo. Timon suggests that he and Pumbaa should forget about the treasure and escape the castle. They go to another part of the castle, only to find a dead end behind a pair of drapes. They then see something moving under the drapes, assuming that it's a ghost. Timon and Pumbaa reluctantly decide to go for their deaths, until Pumbaa pushes one of the wall bricks which sends them to another room, turning out to be a secret passageway.
Timon and Pumbaa go through another secret passageway and find another dead end. The green ghost appears and guides Timon and Pumbaa to a green door, which would lead them to outside of the castle. Timon, however, doesn't believe what the ghost told them is true and he uses a red door instead. The red door sends them to a room with furniture covered in sheets. When Timon sits on a chair, the person disguised as a ghost from before scares the two out of the room and chases them.
Timon and Pumbaa run to a room with five night armors. They hide inside the golden armor. The person enters the room and knocks the knights over like a domino. The green ghost appears and grabs the golden armor. The person in the ghost costume turns out to be Keegan, realizing that it's true that the castle is haunted and that he was not just making it up to pull a scare prank on people.
When Keegan states that Fergus can have the castle and the treasure, Timon asks the green ghost, who turns out to be the leprechaun who is deceased, to lead him and Pumbaa to the treasure. The leprechaun's ghost leads Timon and Pumbaa to the door where there is the treasure, which turns out to be potatoes.