Meanwhile, Shirley was investigating the kitchen dressed like a lunch lady. While looking around, she saw a doorway, opened it, and saw it was the big fridge. Shirley said, "Like I'm going to find anything suspicious in the kitchen. I wonder how the others are doing." Meanwhile, Cassidy looked into her sample of the red goo they found on the stage. Cassidy put a small piece of it under a microscope and tried to see if she could figure out what it was. When she looked into the microscope, she couldn't see anything. Cassidy said, "That's weird. I can't see anything through this microscope. I sure hope the others are having better luck than we are."
Meanwhile, Ricky was mopping the floors around the school and trying to spot anything suspicious. While cleaning, he spotted the mysterious figure they saw last night leaving the basement. Then, the hooded figure ensured the coast was clear, locked the basement door with the key, and went into the boys' room to change. Ricky put a scowl on his face and went to tell the others what he saw. Later, Shirley and The Clue Crackers met in their hotel rooms and reviewed what they saw. Brad said, "OK. Now, did anyone see anything suspicious? For instance, I saw a gym teacher's pager that looked suspicious. I don't think it was a pager at all." Shirley said, "Well, at least you found something. I didn't find anything in the kitchen." Cassidy said, "Speaking of which, I couldn't figure out what that stuff we found on the floor was for some reason." Ricky said, "As for me, I saw the mysterious figure we saw last night leaving the basement." Shirley said, "OK, how about we check out the basement since that's where the mysterious figure was last seen?" Shirley and The Clue Crackers agreed and then returned to the school. Shirley and The Clue Crackers snuck into the school before it closed and hid so no one would find them.
Once the school closed, Shirley and The Clue Crackers came out from hiding, walked to the basement, and tried to open the door, but it was locked. Cassidy said, "It's locked. How are we going to get in?" Shirley said, "Allow me." Shirley took a hairpin from her hair and picked the lock on the door. Once she did, she opened the door, and they walked downstairs to the basement. Once they arrived, they looked around with their flashlights and found a backpack on a table. Shirley said, "What's this?" Shirley opened the bag and saw a black cape inside. Shirely said, "This looks just like the mysterious figure's cape. This backpack must belong to whoever's behind this."
While they were investigating, the mysterious figure found them. The hooded figure said, "You were warned to leave. Now, you must pay the price." Shirley said, "Go. I'll hold him off." Brad said, "Not without me. I'm staying, and there's nothing you can say to change my mind." Shirley said, "Fine. Then let's just run." Brad said, "You can run if you want to, but I'm not leaving without a fight." Shirley and the other Clue Crackers said, "Yes, you are." Then Shirley grabbed Brad and covered his mouth, and they all ran off with him and the backpack they found. Then, the mysterious figure chased them, but Shirley and The Clue Crackers slammed the basement door. Shirley said, "What was wrong with your back there, Brad?" Brad said, "I don't know what got into me.
After they got out of the basement, the tree monster found them in the halls. They all ran for their lives, but the tree monster grabbed Ricky's belt and broke it off. Ricky caught his pants before they fell but thought he needed a new belt. Ricky unzipped the backpack they found, found another belt in it, and put it on. Then he ran away from the tree monster and tried to catch up with his team. Once they lost the beast, they ran out of the school and went to find someplace to hide. After they left, Brad became mad for no reason and said, "I can't believe we got chased out of the school again. I'm going to kick both those creeps' butts." Shirley said, "Calm down, Brad. We'll get them." Brad said, "You're right. And when we do, they're the ones who will pay."
The next day, Shirley and The Clue Crackers went undercover as faculty again, except they switched places this time. Brad went undercover as a janitor, Ricky as a gym teacher, Shirley and Jake went to the science lab to investigate the red goo they found, and Cassidy went undercover as a lunch lady. While Shirley studied the red goo, a fishing line dropped from the ceiling, and it grabbed her backpack. Then, the person holding the fishing pole reeled it in and stole Shirley's backpack, and Shirley didn't even notice. While Shirley was looking in the microscope, she figured out what the red goo was and wanted to write it down on her notepad, but when she reached for her backpack, she saw it was gone. Shirley said, "Where's my backpack?" Shirley looked all over the floor for her bag but couldn't find it. Shirley said, "Someone must have stolen it. But without that backpack, I won't be able to solve this case; it has all my detective stuff in it." Shirley then took a piece of paper, wrote down her data by hand, and put it in her pocket. Shirley said, "I may not have my notebook, but I still have my data." Shirley and Jake then left the science lab and went to find the others.
Brad was cleaning the floors and then got angry for no reason. Brad said, "I can't believe I signed up to go undercover as a janitor. It's the crudest job ever." Meanwhile, Cassidy was investigating the kitchen dressed like a lunch lady. Cassidy then saw a bunch of glowing footprints ending at the wall. Once Shirley and Jake found Cassidy, they saw her knocking on the wall. Shirley said, "Cassidy, what are you doing?" Cassidy said, "Looking for a secret passage. There's a trail of footprints leading into the wall." Shirley and Jake both looked at the ground but didn't see anything. Shirley said, "Are you sure?" Cassidy pushed a loose stone into the wall and opened a secret passage. Cassidy said, "Pretty positive." Shirley, Cassidy, and Jake looked down the underground tunnel and saw a staircase leading down it. Shirely said, "I lost my backpack with my flashlight." Cassidy said, "Don't worry, I still got mine." Cassidy turned on her flashlight, and they all walked down the staircase to see where the secret passage led. While the girls and Jake followed the hidden path, Ricky looked around the locker rooms and left to play basketball in the gym because he felt athletic. Then Ron showed up and saw Ricky playing basketball by himself. Then he took out his pager, and Ricky forgot why he was playing basketball alone. Then he went to the school library and read a book instead.