Meanwhile, Ricky was searching the library for a book to read. While he was searching, Ricky ran into the librarian, accidentally knocked the books she held out of her hands, and they both fell to the floor. Ricky said, "Oh, I'm so sorry. Let me help you with those." Ricky picked up one of the books the librarian was holding, read the title, and kept it to himself. Then Ricky helped the librarian, returned her books, and hid one behind his back. Then the librarian left, and Ricky took a look at the book he took from her stack, reread the title, and left with it.
Meanwhile, Shirley, Cassidy, and Jake all made it to the end of the tunnel, and the monster chased them down. Once they reached the end, they hid so the monster wouldn't find them. Once the beast reached the end of the secret passage, he saw tons of stuff in the room but couldn't find Shirley, Cassidy, or Jake. Then the monster left and walked back down the secret passage. Then Shirley, Cassidy, and Jake emerged inside their hiding place. After the beast went, Shirley, Cassidy, and Jake looked around and found a secret door in the ceiling. Shirley said, "I guess this is the only way out. Let's go." Shirley opened the hidden door and opened a trap door on the school's floor. Then Shirley, Cassidy, and Jake all climbed out and looked at where they were. Shirley looked in front of her and saw the door to the basement. Shirley said, "So this is how the tree monster got to us so fast last night." Cassidy said, "Looks like we found ourselves a clue. I wonder how the others are doing."
Brad slowly walked backward up to Shirley, Cassidy, and Jake and ran into them. Brad then turned around, saw Shirley, Cassidy, and Jake, and started to cry. Brad said, "Oh, hi, girls. I wouldn't look at me if I were you. My undercover position makes me look so awful." Cassidy said, "That may be true, but you're still yourself." Brad became happy and said, "Really? Thank you." Then Ricky showed up and told them he had some evidence to show them. Later, Shirley and The Clue Crackers met in their rooms and reviewed their clues. Brad said, "OK, what are the facts we know?" Shirley said, "Fact 1, I found out what that residue is. It's cherry gelatin; it probably got splattered when the monster dropped it." Cassidy said, "Fact 2, we found a secret passage leading to the hallway where we saw the monster, which I say we check out again." Ricky said, "Fact 3: I found this in the librarian's stack of books." Ricky gave the book to Cassidy, and Cassidy thought she recognized it. Cassidy said, "It's a diary that doesn't belong to the library." Shirley said, "Why would a librarian have that?" Cassidy said, "She wouldn't unless she knew who it belonged to." Cassidy gave the book to Shirley, and Shirley read whose diary it was." Shirley said, "Principal Jackson." Brad said, "We got to check him out." Cassidy said, "So tonight, we'll sneak into the school again and split up. Shirley and Jake will check out Principal Jackson's office for clues. Brad, Ricky, and I will go to the secret passage and look around." Brad said, "Agreed." Ricky said, "Also agreed." Shirley said, "I'm in, too." Cassidy said, "Good."
Shirley and The Clue Crackers all went to the school after dark. Once they arrived, Shirley opened the window to the principal's office and pulled Jake in. Meanwhile, Brad, Cassidy, and Ricky snuck in through a different window leading into the hallway. Then Cassidy opened the trap door on the floor, jumped down it, and entered the secret passage with her flashlight. Then Brad and Ricky jumped down it, took out their flashlights, and looked around the hidden passage for clues. At the same time, Shirley and Jake searched the principal's office for clues. Shirley turned on a light so she could see and looked at some of the books on Principal Jackson's shelf. Shirley read some of the titles, but none were suspicious, so she checked out his desk. Shirley found a few graded papers, personal records, and newspaper articles. Shirley said, "Still nothing suspicious."
Meanwhile, Brad, Cassidy, and Ricky were all investigating the secret passage. While they were looking around, they found a bunch of boxes with labels and read what was in them. Cassidy said, "Roman candles, dynamite, fireworks, and explosives. What would all this stuff be doing down here?" Brad said, "I don't know, but I think something is happening here that doesn't quite meet the eye." While they were looking around, the mysterious figure found them. The mysterious figure said, "So, you stumbled upon my secret. Too bad you won't be around long enough to tell anyone." Ricky became brave and got ready to fight the mysterious figure. Ricky said, "Bring it on." The mysterious figure brought a rope tied into a lasso, spun it in the air, threw it at Brad, Cassidy, and Ricky, and lassoed them. Then he pulled the rope, and Brad, Cassidy, and Ricky fell to the ground. Ricky then used his pocket knife to cut the line and got ready to fight the mysterious figure again. Then he became afraid and didn't want to fight the mysterious figure anymore. Then, all three of them ran for their lives, and the mysterious figure chased after them. Once they reached the tunnel's end, they climbed back up to the trap door and ran out. Brad and Cassidy tried closing the trap door, but the mysterious figure kept trying to push it open so he could get out. Ricky said, "Hurry, close it, close it." Brad became mad and said, "We're trying our best, so back off." Brad then kicked the mysterious figure back down the secret passage, and once he did, he and Cassidy shut the door and ran off before the mysterious figure could come after them. Cassidy said, "That was close."