"I found a whole bunch of cool old picture frames in my uncle's barn," said Rick. "I was thinking we could make a creepy portrait gallery with them, you know, with fake spider webs draped all over them?"

"Excellent," I said admiringly. "I bet Claudia would love to do some of the portraits. She could probably make them look as if their eyes were following you around."

"I shopped for the basics," Todd reported. "I bought a bunch of red light bulbs and about ten rolls each of purple and red streamers."

"We can store everything in my cla.s.sroom," said Mr. Rothman. "Anything else?"

"My grandmother has this incredible gla.s.s punch bowl," Grace offered. "It's huge, and it looks just like something Morticia would use at a party. Anyway, she said we could borrow it."

"Great," said Todd enthusiastically. "Maybe we can figure out some way to use dry ice so it looks like the punch is smoking. I'll talk to one of the people on the refreshments committee."

By the time our meeting broke up, everybody was excited about our plans for the dance. Except c.o.kie. She still didn't like the Addams Family theme, but she was stuck with it. As far as the rest of us were concerned, we were beginning to feel as if we were all set for the dance.

That's why it was such a shock when Rick ran to me on Friday morning as I was heading for social studies cla.s.s.

"Did you hear?" he asked me. His face was pale.

"Hear what?" I asked.

"About what happened to all that stuff Todd bought. You know, the streamers and the light bulbs?"

"What about them?" I asked.

"Gone," said Rick. "The streamers are cut into shreds, and the light bulbs are smashed."

"You're kidding!"

He shook his head. "I wish I was," he said. 'Todd is really b.u.mmed."

"I don't blame him. Was it the Mischief Knights?"

"If it was, they didn't leave a note or anything. But I don't think it was them. It's not their style."

I nodded. He was right. "But who, then?"

Rick shrugged. "Don't know," he said. "Anyway, I have to run. We'll figure it out at the next meeting." He took off down the hall.

I headed in the opposite direction, walking slowly and thinking hard. Who would want to wreck the decorations?

Suddenly, I had an awful thought. What if c.o.kie were right about Grace, that Ted really didn't exist? Maybe Grace was trying to sabotage the dance, so she wouldn't be caught in a lie.

I shook my head. It was too ridiculous. Grace would never be so destructive. Would she?

"Nah," I said out loud. And as I walked into social studies cla.s.s, I reminded myself not to jump to conclusions. The vandalism was terrible, but it was probably just a one-time tiling. Anyway, it would be wrong to blame it on an innocent person.

Chapter 7.

"So? What do you think?" Claud stood back from her bed, where she'd laid out two of the five huge red-and-purple posters she had made. She had asked me to come to Monday's BSC meeting a little early so she could show them to me.

"They're awesome," I said finally. "They're the best posters I've ever seen." They were, too. When I had asked Claudia if she wanted to help out by making the posters for the dance, I had known she'd do a good job. But I never expected the posters to look as professional and as eye-catching as they did. "These look like something you'd see plastered on a bus in New York," I said. "Like an ad campaign from a top agency."

"Well, you helped design them," Claud pointed out. "You're the mastermind. All I did was follow your orders."

"The whole committee designed them," I reminded her. "Well, except c.o.kie. She didn't like this idea."

"She'll like it now, when she sees the posters," Claudia said.

"I wouldn't count on it."

Guess what? I was right. c.o.kie didn't like the posters. She saw them the next morning, when the decorations committee met half an hour before homeroom in order to hang the posters in the halls.

Rick thought the posters were "incredible."

Todd said they were "wicked."

Grace couldn't believe how "artistic" they were.

c.o.kie? All she noticed was that Claudia had misspelled "masquerade" on one of the posters.

That made me mad. Claudia had worked hard, and she'd been especially careful about her spelling. You have to understand that for Claud to spell only one word wrong on five posters is pretty dose to a miracle. But I didn't say anything to c.o.kie. I just ignored her, and so did Grace, Rick, and Todd. Using a step-ladder borrowed from the janitor, we hung the posters up; two in the halls near the cafeteria, one near the main entrance, one by the gym, and one by the auditorium. They looked amazing.

"This dance is going to be the best!" Grace said, stepping back after we'd hung the last poster. "Ted's going to be really impressed," I knew c.o.kie was giving me one of her Looks behind Grace's back, but I pretended not to see it. "I'm sure he will be," I told Grace. I wanted so badly to believe that there was a Ted, so I wouldn't have to believe that Grace could have destroyed the streamers and light bulbs. Now that I was with her, it was almost impossible to picture her doing such a thing. Grace has such a sweet, honest face.

"Yeah, well, Carrie had a sweet face, too," said Claud as she pulled out a purple marker and started on some careful lettering. "And look what happened at her school!"

I shuddered, remembering. Claudia and I rented the movie, Carrie, a few months earlier, and I don't think I slept for a week afterward. I like scary movies, but that one was over the top.

It was Wednesday afternoon, and my friends and I were gathered in Claudia's room for a BSC meeting. But we weren't talking about clients or schedules or any other kind of BSC business. We were talking about the latest bizarre episode at SMS.

Here's how I found out about it: When I arrived at school that Wednesday morning, Todd Long met me near the side door. "You won't believe it," he said. "I don't believe it."

"What?" I asked. But Todd wouldn't answer. He just led me through the halls until we were near the cafeteria. The floor was covered with tiny bits of red confetti. "So?" I said. "Somebody made some weird mess here. Is this what you wanted to show me?"

Todd didn't answer. He cast his gaze around at the walls, and I followed it. That's when it hit me. The posters! That wasn't confetti on the floor. It was Claudia's beautiful posters, all ripped into minuscule bits.

I put my hand over my mouth. I couldn't speak.

"I know," Todd said grimly. "They also tore up the one near the auditorium and the one by the main entrance."

"But why?" I asked. "What a horrible tiling to do."

"That's not the worst of it," Todd said. "I want you to see something else." He led me through the halls again, this time toward the gym. I had no idea what he was going to show me, but I did know one thing: I probably didn't want to see it.

"Nice, huh?" Todd asked as we rounded the last corner.

I looked up at the poster we'd hung there and drew in a sharp breath.

"At least they left one of them up," Todd said. He was trying to lighten the situation, but it didn't work. What I was seeing sent chills down my spine, and no amount of joking was going to make those chills go away. Spray-painted across the poster, in drippy, red, b.l.o.o.d.y-looking letters was this message: Todd was looking at me, as if he expected me to say something, but I couldn't. I was too creeped out. Instead, I helped him take the poster down and roll it up. We'd have to make more posters - I knew that much - but would they just be ruined too?

Finally, as we walked down the hall toward our lockers (it was nearly time for homeroom), I thought of something. "Do you think it might have been the Mischief Knights?" I asked Todd.

He shook his head slowly. "I almost wish it had been them," he said. "That would make this easier to understand. But if they did it, they sure didn't want anyone to know. They didn't leave a note, or their initials, or anything."

I remembered what Rick had said about the torn-up streamers, that it wasn't the Mischief Knights' style. I'd thought he was right about that, and the same thing applied here. Ripping up posters isn't mischief; it's vandalism, plain and simple. And writing on them is vandalism also, especially if you're trying to scare people.

And people would have been scared, if they'd seen the poster, or heard about what it said. But Todd and I agreed to keep it as quiet as we could. That's why I had waited until the BSC meeting to tell my friends about it, and to show them the poster, which I'd stuck into my backpack after we'd rolled it up.

Claudia was already at work on some new posters - that's what she was doing with the purple marker - while we talked about what had happened and tried to guess who had done it.

Claudia had a suspect in mind. "Little Ms. Mason," she said angrily. "Face it, she never liked my posters to begin with. I wouldn't put it past c.o.kie to take advantage of the fact that all those pranks have been happening at school. She knew she could do some vandalism and blame it on the Mischief Knights."

"I don't know," Kristy said, tapping her pencil against her teem. "I think the Mischief Knights really might have done it. Maybe that other stuff they did was just for starters."

"You mean they were leading up to bigger things?" asked Abby, from her perch on Claud's art books. She was playing with one of the Twizzlers Claud had pa.s.sed around. She had pulled the strands apart, and now she was braiding them back together.

"Right," said Kristy. "Just when everybody was starting to enjoy their fun and games - wham!"

"What about Grace?" Jessi asked. She was talking into the floor as she did one of her painful-looking ballet stretches. "Is she still a suspect, Stace?"

"Well, I don't know," I said. "It really seems unlikely. She's just too sweet, even if she is c.o.kie's best friend. I can't imagine her tearing into those posters."

"But somebody did it," Mal said. "And whoever it is probably looks just as sweet as Grace. But underneath, he - or she - is different."

"Oohh, creepy," said Abby, grinning. 'I'll never look at my cla.s.smates the same way again. I'll always be wondering about that nasty 'underneath' part."

"You don't have to look far, with c.o.kie," Claudia muttered.

"What about the streamers and the light bulbs, though?" I asked. "Why would c.o.kie have ruined them?"

Claudia gave me a Look. "Come on, Stacey," she said. "Think about it."

I knew the answer almost before she finished speaking. "Because she hated the color scheme," I said slowly. Claudia nodded triumphantly.

"But is that really a reason for doing such a terrible thing?" Mary Anne asked suddenly. We all turned to look at her, and she blushed. She had been quiet during our meeting so far. "I've been thinking," she continued. "Maybe we're limiting ourselves by only looking for suspects at SMS."

"Where else should we look?" Kristy asked.

"Well, we could look in the community," Mary Anne said in a small voice. Then she sat up straight, and her voice became stronger. "We could look at Mr. Wetzler."

I gasped. "Mr. Wetzler! Sure! He's a definite suspect. Good thinking, Mary Anne."

Our meeting broke up soon after that, even though we hadn't come up with any answers. But less than twenty-four hours later, we were back in Claudia's room for an emergency meeting and we were talking about suspects again. Why? Because there had been another act of vandalism at the school. Somebody went wild with the red spray paint again, only this time it wasn't on a poster. It was on the walls of the gym. Here's what it said: $10.

That's all. $10. In figures about eight feet high. n.o.body had a due what it meant. Especially Mr. Kingbridge, who made a special announcement to plead for an end to the vandalism, and to tell us that he might cancel the dance if it didn't stop. That's why Kristy called the meeting.

"Okay," she'd said as soon as we had gathered in Claudia's room after school. "We have a genuine mystery on our hands. And the BSC never leaves a mystery unsolved, right?" She looked around expectantly.

"Right!" we replied.

"Right," Kristy echoed. "Let's do it. We don't want this dance to be canceled, do we?"

"No way," said Claud, pulling out a notebook. "Let's start. I'll make a list of suspects."

After that, we returned to the same discussion we'd had the day before. Only I wasn't contributing to it. I was remembering the "tragedy" Mr. Wetzler had mentioned in one of his wacky letters to the editor. And I was thinking about something Mr. Kingbridge had said when he first announced the dance. He'd mentioned something about "erasing those unpleasant memories of the past." What tragedy? What memories? Somebody seemed determined to make sure the dance never took place - but what if it wasn't someone who went to SMS now? What if it was someone else, someone who remembered something awful about the last Halloween masquerade, twenty-eight years ago?

Chapter 8.

As soon as our emergency meeting ended, Claudia dashed over to the Arnolds' for a sitting job. She arrived at two minutes to five: two minutes early. Mr. and Mrs. Arnold were driving to Stamford for dinner with Mr. Arnold's boss, so Claud would sit for the eight-year-old Arnold twins, Carolyn and Marilyn, from five until around nine. That meant Claudia would be giving the girls dinner, which was fine with Claudia, since she hadn't had a chance to grab a bite. Mrs. Arnold always leaves plenty of good food and urges her sitters to eat as much as they like.

Claudia smiled to herself as she walked to the Arnolds' door. A life-sized skeleton (with glowing eyes) dangled from the porch ceiling, and four carved jack-o'-lanterns with toothy, jagged smiles decorated the porch stairs, A string of orange pumpkin lights outlined the front door, and there were white ghost and black cat cutouts on all the windows. The Arnolds love to decorate their house for holidays. You should see it at Christmastime.

Mrs. Arnold answered the door when Claudia rang the bell. She looked elegant in her black velvet skirt and white satin blouse.

"Love the jewelry," Claudia said.

"Thanks," Mrs. Arnold replied, smiling as she touched one of her dangly orange ear- rings, which was in the shape of a tiny pumpkin. She also wore a necklace with a pumpkin pendant, and a bracelet with dangling pumpkins. Mrs. Arnold tends to go a little overboard in the accessories department.

Mr. Arnold appeared behind her. "Ready?" he asked as he shrugged into his coat.

Five minutes later, they left and Claudia was headed for the Arnolds' bas.e.m.e.nt rec room. "Carolyn?" she called down the stairs. "Marilyn? Your mom said you were down here. What's up?" There was no answer. "Guys?" Claudia called. Still no answer. Claudia started down the stairs, and soon she spotted the twins. They were hunched over their low art table, working hard on something. It was clear that they were so absorbed in their project that they hadn't even heard her call. "Hi, Carolyn," Claud said. "Hi, Marilyn. What are you guys doing?"

"We're busy!" Carolyn said. "We have to fix this thing," Marilyn explained.

"Fix what thing?" Claudia asked, trying to peek at what they were working on.

The twins exchanged serious glances, and Claudia was struck all over again by with how much they look alike. When we first met the twins, we had trouble telling them apart. We had to remember that Marilyn was the one with the tiny mole beneath her right eye, and that Carolyn had a similar mole under her left eye. Back then, Mrs. Arnold was dressing the girls alike, and they shared a room. Over time, though, they've begun to express their separate personalities. Now they have their own rooms, and each room is decorated differently. They have different hair styles (Carolyn's is much trendier), different ways of dressing (Marilyn wears simpler clothes), and totally different interests. (For example, Marilyn is a dedicated piano student, while Carolyn, who is tone-deaf, is fascinated with science.) As you can imagine, we no longer have any trouble telling them apart.

The twins are very dose, though. Sometimes, when they want to exclude other kids (or sitters), they communicate in a made-up language no one else understands. And they often communicate without speaking at all. That's what they were doing down in the bas.e.m.e.nt that afternoon, as Claudia waited to find out what they were up to. They looked into each other's eyes for just a few seconds, then they nodded and Marilyn said, "Come see!"

Claudia moved forward to take a look. She saw a board with wires and flashing lights. Attached to it was a funnel, and attached to that was a flashlight. "Cool!" she said. "What is it?"

"A ghost-finder," Marilyn said.

"Marilyn," said Carolyn sternly. "It's not a 'ghost-finder,' It's an ectoplasmic turbulence detector."

Claudia nodded. Suddenly it was all clear. The Arnold twins had been watching Ghost-busters, too.