So, Kristy is hanging out at home and enjoying the sunshine watching Nannie and Watson work in the garden when Shannon and Abby stop by. Abby is still complaining about that time she bought a copy of the test and did not get expelled from school and how the guy who sold it to her is a jerk. There's also a brief mention of someone named Troy Parker. He was recently suspended but no one knows why.
Kristy goes back to school and thinks about how much she hates Cary Retlin. He possibly – she has no proof – stole her math homework, changed all the answers, and put it back in her bag. He also manages to get her watch right off her wrist. After the two fight, he offers her a deal. If the BSC can solve a mystery of his choosing, he'll give her back the watch and leave her alone too. Since Kristy thinks she can do anything, she agrees without even talking to the club members first.
Cary leads them on a treasure hunt that starts with the clue: Get Your Mother (understands). After trying way too many things, they realize it refers to the gym stands. There, they find another clue and see Troy wearing mismatched clothing. It must be a truly terrible outfit because even Claudia makes fun of it, and you know the kind of crap she wears.
You may remember the Mischief Knights, who are now back in action. Someone leaves rude comments on a teachers car with the MK initials signed in green, which is weird because Cary always used red. It's also weird because the comments are directed at the principal but it's not his car. The next clue leads them to the boiler room, where they find a clue directing them to the old equipment shed. Remember when Kristy was kind of involved in burning it down? She assumes Cary chose it as a dig to her, even though he didn't live in Stoneybrook at the time.
There's also a big controversy going on with the teachers, the school board, and some locals. The teachers want a raise, the school board won't give them one, and they finally announce that they may go on strike. Kids and their parents aren't happy because it would mean summer in July. Mr. Oates, the board chairman, keeps pointing out all the stuff happening at SMS and how it proves the teachers don't deserve a raise because they can't control their students.
Other MK stuff happens. Someone pulls the fire alarm and leaves a green MK next to it. Kristy finds the bathroom overflowing one day with the MK next to it again. She begins suspecting the poor old janitor, who I assume is only a suspect because they want a bunch of red herrings. The next clue leads them to a specific classroom, where they see the poor old janitor again.
Their next clue leads them to the computer Claudia used for her old personals column. Cary set up a spelling test for her that spits out the next clue when she finally passes it. This clue takes them to the auditorium. They see Mr. Oates with a journalist talking about how the school is out of control and the teachers are doing nothing.
Kristy believes that the person responsible for all the MK stuff is Cary. When they get caught in the auditorium at the same time someone pulls another prank, she tells the principal all her evidence. Her “evidence” is lame at best. Cary was supposedly on a bathroom break during one prank and had access to green chalk. He doesn't really believe that they would ruin the sets from the last school play, so he takes her evidence. Kristy notices yet another MK on her way out the door.
Cary is so angry that he confronts Kristy and lets her know that he has an alibi for every prank, including tutoring another student at one point. He gives them one last clue, which leads them to the final clue, which asks for the head of the false MK. Mary Anne finally realizes that the person doing all this stuff is color blind, which explains why he/she chose the wrong car and used the wrong color chalk. The only color blind person they know is Troy Parker.
Since they can't just blame him like they do everyone else, they ask for Cary's help breaking into his locker. They find all the evidence needed to prove he was the MK culprit. Troy finds them going through his stuff and confesses just as the principal shows up. The school board agrees to meet again to come up with a solution to the raise situation, and Kristy lets Cary keep her watch.
In other news, Kristy comes up with a “brilliant” idea to let their charges do a scavenger hunt too. They'll assign sitters to groups of chargers, pick a theme for the day, let the kids find items on the list, and award points for the most creative choices. This leads to random stuff like kids carrying around tree branches for a clue on something that holds paper and finding sweat socks for something that stinks on and off the court. There's no real resolution either. The BSC decides to choose a few winners, but we don't really see what they get.
*Kristy makes a point of saying that Cary wasn't at SMS during the whole softball equipment shed fiasco, but he also wasn't in school when Claudia did the personal ads. Given that it's pretty much never mentioned after, how would he know about it?
*Why would the chairman make a big deal out of how the teachers can't control the students? Did he want to fire them all and start all over again?
*You would think they would at least get a warning for breaking into someone's locker, but I guess you never mess with the BSC.
*Abby seriously needs to get over the whole cheating thing. She's the one who bought the test, and I'm sorry, but there is no way you would confuse a study guide with a copy of the real test.
*Troy is literally only mentioned like twice in the book before they out him as the MK vandal. It's pretty ridiculous.
*This is probably my least favorite mystery so far. It felt like very little happened, there were too many suspects that made no sense, and the end was a cop out. They seriously suspected the janitor of being a vandal?
*As for the teachers' raises, can't Watson just throw some money at the situation and make it go away? LOL