The Curious hides at the back of a school bus and watches as the kids get off.
Greg is sad at having become distant from his former best friend Dave, who has joined the football team and doesn't want to spend time with him any more. Dave’s new friends, the football players, including Dave’s new best friend, Kelsey, the well-built Captain, also bully Greg. Dave arrives in class late and covered in mud, but refuses to say what happened to him. Greg tries to ask if Dave is OK, but Dave is angry that Greg pointed him out to the teacher. When Dave is missing from class again, Greg makes excuses to leave and follows him. Dave heads into someone's yard, picks up a trash can lid and stick to use as weapons, and charges inside. Greg follows him into an old, abandoned shed and unexpectedly falls through a wormhole into a pool full of swamp water elsewhere in the town.
Greg goes back to the shed and finds Dave, who warns him to be quiet. He implies there is some kind of creature living in the shed. The boys leave and run into Dave's Aunt Abigail, who thinks Greg has come to help Dave clean up. Dave explains that the shed is full of junk that his late grandfather hoarded; he is determined to get rid of the creature for Aunt Abigail's safety. Greg promises to help Dave and the two venture into the shed again. They encounter the creature, and observe that it seems to be afraid of light; but end up back in the pool.
Having caught the creature on film, Greg and Dave research and discover that the creature is known as an Elemental Shade and its only weakness is light. Subsequently Greg devises a machine to target the monster with music and bright light. Dave lures the Shade while Greg rigs up his machine, only for them to get ejected into the pool once again; however, Greg is still holding onto the rope he rigged up to the machine. He is able to pull the rope through the wormhole, triggering the machine and destroying the Shade.
Greg and Dave repair their friendship and finish cleaning out the shed. Aunt Abigail asks for their help in cleaning up the basement as well, but when the boys open the door, they hear another creature inside.
The Curious picks up a disco ball that Greg and Dave had found in the shed, and begins dancing to the music they used to help defeat the Shade.
This episode contains examples of:
- Alpha Bitch: Kelsey is a male version of this.
- Bromance: Greg discusses this in an essay he wrote for school about friendship.
- Cool Kid-and-Loser Friendship: Greg and Dave.
- Dance Party Ending: At the end, the Curious takes Greg and Dave's disco ball and starts dancing.
- Here We Go Again!: The ending has the boys open the doors to the basement, only to be attacked by another elemental shade.
- Jerk Jock: Dave's new friends on the football team.
- Lighter and Softer: After some darker episodes, notably Marti and Bravery Badge, this is refreshingly light and has a happy ending with a lot of comic relief.
- Nerd Glasses: Greg wears them.
- Period Piece: Judging by the clothing, technology and setting, this episode appears to be set in the 1970s.
- Trash of the Titans: The condition of the shed (and apparently basement) due to Dave's grandfather being a hoarder.
