The Clue Crackers were decorating a high school for Christmas. The boys decorated the inside while the girls decorated the outside. While Judy was decorating, someone on a hovercraft kidnapped her. Cassidy shouted, "JUDY!" Cassidy ran after her and tried to catch them, but the driver activated the turbo speed and ditched Cassidy. After they left, Cassidy ran back to the school to warn her team. Once she returned, she found Brad and told him what had happened. Cassidy said, "Brad, we have a mystery." Brad said, "What is it?" Cassidy said, "Someone on a hovercraft just took Judy, and we need to find her." Brad said, "We will, but we're going to need someone to take her place until we find her." Ricky said, "I know just the girl for the job." Ricky showed his team a magazine with a picture of a girl, and Cassidy read it. Cassidy said, "Shirley Hudson? The #1 solo girl detective in the world?" Ricky said, "She can do it. She can help us." Cassidy said, "I don't think we'll need her. We're three detectives with a dog. We can handle it."
Brad said, "It couldn't hurt to have some backup. Let's call her." Brad called Shirley Hudson and briefed her on the mystery. Brad said, "Hi, Shirley. My name is Brad. I'm calling from New Orleans High, and we need your help. Someone on a hovercraft kidnapped our friend, and we need you to help us find out who did it." Shirley said, "You'll be helping?" Brad said, "We're detectives too. We need someone like you to take our friend's place in the group until we find her." Shirley said, "I'm on my way."
Once Shirley got to the school, she jumped in through the window and hit her head on a wall. Shirley said, "That's got bruise written all over it." Once Shirley arrived, she stood up and saw The Clue Crackers waiting for her. Shirley said, "Hi, I'm Shirley Hudson." Brad said, "Hi, I'm Brad. These are my friends, Cassidy, Ricky, and Jake. We're the detectives who called you." Shirley said, "OK, so where should we start?" Cassidy said, "As a witness, I say we check out the crime scene."
Shirley and The Clue Crackers went outside to check out the crime scene, and once they did, a Christmas tree in the woods came to life and spotted them investigating. While looking around, Shirley found a silver hairbrush on the ground. Shirley said, "What's this?" Brad said, "It's a hairbrush." Cassidy took it and said, "Not just any hairbrush, Judy's hairbrush. Which means she must have dropped it when she got taken." While Shirley and The Clue Crackers were investigating, someone planted a bomb and a piece of paper in Shirley's car. Shirley then put Judy's hairbrush in her backpack and started to hear ticking. Shirley said, "Everyone quiet." Cassidy said, "Why?" Shirley said, "Listen." The Clue Crackers started to hear ticking, turned around, and saw it coming from Shirley's car. Brad shouted, "Fire in the hole!" Shirley and The Clue Crackers took cover away from Shirley's car and got on their knees while covering their ears. Then Shirley's car exploded, and a note fell from the sky. Shirley grabbed the letter and read it out loud. Shirley said, "Stay away from New Orleans High and never return. If you choose to remain, you'll lose more than just your car and your friend. Tree Monster." Brad said, "Who's the Tree Monster?" Then, a living Christmas tree came out of the woods, jumped in front of them, and roared at them. Cassidy said, "Does that answer your question?" Brad said, "Sadly, yes. RUN!"
Shirley and The Clue Crackers ran for their lives, and the tree monster chased them back into the school. Once they returned to the school, the tree monster followed them to the auditorium and into the doorway leading backstage while a play was happening. While the show was happening, the actors sang together, but Shirley and The Clue Crackers ran out on stage, and the audience got confused. Ricky said, "Go drama club." Brad said, "Run, everyone, run." Then, the tree monster jumped out on stage and scared everyone in the auditorium. Then, everyone ran out of the school, including Shirley and The Clue Crackers. Shirley said, "Now that everyone is scared out of the school, I don't think they'll return." Brad said, "Then maybe we should come back tonight and investigate." Cassidy said, "Agreed." Ricky said, "Just one question. Where are we going to stay while we work on the case?" Shirley said, "I know just the place." Shirley checked all five of them into a hotel, and they got two connecting bedrooms. Shirley and Cassidy slept in the first, while Brad, Ricky, and Jake slept in the other. Shirley said, "OK, now that we got checked in, let's get to the school and look around."
Once it got dark out, Shirley and The Clue Crackers returned to the school to investigate. They tried opening the doors, but they were locked. Shirley said, "They're locked." Brad said, "Of course they are; no one's here after hours." Cassidy said, "So, how do we get in?" Shirley said, "Stand back." Shirley took her credit card from her wallet, put it between the doors, and picked the lock. Then Shirley opened the door and said, "We're in." Cassidy said, "You know how to pick locks?" Shirley said, "I'm a detective; of course I do." All five of them walked in and stopped for a minute. Brad said, "OK, gang, let's split up and search for clues." Shirley said, "Good idea. I'll go with Ricky, check out the hallway the monster chased us down, and see if he left any clues." Brad said, "OK. And Cassidy, Jake, and I will check out the auditorium and see if there are any clues from when the monster attacked."
Both groups split up and went with the people in their groups. Shirley and Ricky walked down the hallway they had been chased down earlier and cast their flashlights on the floor and walls, hoping to find clues. Ricky threw his light on the floor and saw a green glove resembling the tree monster's hand and arm. Ricky picked the glove up and said, "Hey, look what I found." Shirley took the glove and looked closer at it with her flashlight. Shirley said, "What's this? A green glove? And it has words inside. It says, 'If found, please call 555-0138'." Shirley thought about it and said, "Hmm."