Sure enough, there was Grace (dressed as Snow White), dancing with an incredibly cute guy who was dressed as Prince Charming. I saw them dance right by c.o.kie, but Grace didn't even glance at her former best friend.

"So Ted really does exist," I murmured to myself. I was happy for Grace, and it was a relief to be absolutely certain that I'd been wrong to suspect her of the vandalism.

I saw Todd and Rick standing by the refreshments table, next to the steaming punch bowl. Todd had come as Fred Flintstone, and Rick was Barney Rubble. Their costumes were a riot.

It was so much fun to see everyone dressed up that I almost forgot my fears about the evening. But then Mr. Rothman danced by, dressed as a football player (including helmet and shoulder pads). He gave me a look over his date's shoulder, and I knew he hadn't forgotten. Then he and his date (a subst.i.tute home ec teacher named Ms. Bryan, who was dressed as a vampire, in a long, black cloak with a hood) whirled away, leaving me with a queasy feeling.

Liz Connor might be somewhere in that crowd, and if she was, she could be ready to make trouble. Or the troublemaker might be Mr. Wetzter, or the Mischief Knights. Or - gulp - the ghost of Mr. Brown. And there wasn't just a middle school dance at stake. This was serious business. If one of those people pulled a prank and the crowd panicked, people could be hurt or even killed.

It had happened before.

I was lost in thought, but Robert brought me back to reality by asking me to dance. I hadn't told him anything about my fears, since I wanted this night to be fun. I just smiled at him and followed him onto the dance floor. Robert is an excellent dancer. I think it's be- cause he's a- good athlete and knows how to move his body without feeling self-conscious. We danced to three fast songs until I was out of breath, and then settled into a slow one. I rested my head on Robert's shoulder and relaxed. For a few sweet moments, I forgot everything but the feeling of Robert's arms around me.

Then I felt his arms tighten. "Whoa!" he said. "Check it out!"

I lifted my head and looked around. "What?" I asked.

"That guy's costume is great," he said, nodding toward a figure looming nearby.

I looked closer and realized it was Cary Retlin, dancing with Sabrina Bouvier, who was dressed as Cleopatra. Gary's face barely showed through a peephole in the huge papier-mache horse head he wore. "A horse?" I asked.

"I think he's supposed to be a chess piece," said Robert. "You know, a what's-it-called?"

"A knight!" I said, gasping. "That's Cary Retlin, and he's supposed to be a knight." Suddenly, it all became dear. The mischief that had gone on during recent weeks had started after Cary moved to Stoneybrook and came to SMS. Cary Retlin was the leader of the Mischief Knights! He had to be.

Then I remembered something else. I re- member how I'd laughed at him his first day in my English cla.s.s when he fell off his chair. Did he resent me for that? Maybe he did, and maybe he knew I was on the decorations committee for the dance. If so, he had a motive for sabotaging our hard work.

"Robert," I whispered. "Let's switch partners with them. I want to talk to Gary."

"Sure," Robert said. "I always wanted to dance with Cleopatra." He tapped Cary on the shoulder. "Mind if I cut in?" he asked, and before Cary could answer, Robert had taken his place with Sabrina, leaving Cary standing there alone. I held out my arms, and soon we were dancing together. The band shifted into a faster song.

"I know your secret," I whispered to him.

He didn't answer. He just spun me around the dance floor. He was a pretty good dancer.

"I know you're a Mischief Knight," I said, after we'd spun past the stage where the band was playing.

"Do you?" he asked. I couldn't see his face, but I had a feeling he was smiling.

"You're the one who thought up all those pranks," I said. "Aren't you?"

"I don't know," he said teasingly. "Am I?"

It was infuriating. "You are!" I cried.

"Maybe I am and maybe I'm not. Either way, you have no way of proving anything."

He was right. I had a feeling that SMS, and the BSC, hadn't heard the last of the Mischief Knights.

Robert cut back in on Cary and me before I had a chance to ask any more questions, such as whether or not the Mischief Knights were responsible for vandalizing our dance decorations. It was probably just as well, because he never would have given me a straight answer anyway.

Robert noticed that I was agitated, but when he asked me what was the matter, I told him I was okay. I was, too. Or at least, that's what I told myself. Robert and I danced to every song for a long time after that, which was fine with me. I didn't want to talk, and I didn't want to think. All I wanted was to have a good time and to end the dance without anyone getting hurt.

The evening flew by in a blur. I know my friends were having fun, because every so often I'd see one of them dance by, smiling. Even Mr. Rothman was having fun, from what I could tell. He and Ms. Bryan in her long black cloak were dancing up a storm.

Finally, the band announced that they were going to take a short break, and that when they came back they'd play for the last dance of the night, when everyone would take off their masks and "reveal their ident.i.ties." That was kind of silly, since everybody already knew who everybody else was, but it would still be fun. I headed for the girls' room to make sure my makeup hadn't melted underneath my mask.

When I walked in, I saw Ms. Bryan standing near the towel dispenser, hugging herself. All she was wearing was a camisole and leggings, and she looked cold - and upset.

"Are you okay?" I asked.

"Oh, I'm fine," she said. 'It's just that somebody spilled onion dip all over my cloak, and then followed me here. When I took it off to dean it, they grabbed it and ran off. Now I'm stuck in here. I can't go back out there dressed like this."

I stared at her. "Somebody stole your cloak?" I said slowly.

Just then, I heard the music start up in the gym. The last dance was beginning. Something clicked in my mind. All the pieces of the puzzle flew into place. "Oh, no!" I cried.

I dashed into the gym and stopped short when I saw Mr. Rothman dancing with a woman in a long, black cloak! I ran toward them, without even thinking about what I was going to do or say, but before I could reach them the bandleader announced that it was time for "the unmasking."

"Would everybody please reveal your ident.i.ty when I count to three," he said. The drummer began a drumroll, and the lights went out. The idea was that when the lights came back on, everybody would be revealed for who they really were. I knew it was planned. This was not a blackout. But all the same, it was frightening - especially when somebody screamed.

The lights flickered on as suddenly as they'd gone off, and I looked over at the spot where I'd seen Mr. Rothman. He was still there, only now he was as white as a sheet. Standing in front of him was a woman wearing a tattered and torn pink fairy princess costume. A black cloak lay at her feet.

Michael Rothman stared at Liz Connor, and she stared back at him with a wild gleam in her eyes. She smiled slowly. Even from where I was standing, it was obvious that Liz Connor was very, very crazy.

Chapter 15.

"So then what happened?" Shannon leaned forward eagerly.

It was Monday afternoon, and, while we were supposedly having a BSC meeting in Claud's room, we were actually rehashing the events of the weekend. And, naturally, the first thing we did was to fill Shannon in on everything that had happened at the dance, since she was the only BSC member who hadn't been there. She had come to our meeting just to hear about it I don't know how she made sense of any of it, since we were all talking at once, but at any rate we had told the story up until the point when the lights came back on and Liz Connor was standing in front of Mr. Rothman, dressed in her tattered fairy princess costume.

"It was awesome," said Claudia. "Everybody just stopped what they were doing and stared at them." She shook her head and popped three red Peanut M&Ms into her mouth.

"It was so creepy," said Jessi, with a shudder.

"Majorly creepy," agreed Kristy. "That woman was out of her gourd. It was, like, what's she going to do next?"

"Even the people who didn't know anything about the story were freaked out," said Mal. "Especially when she started laughing."

"She started laughing?" asked Shannon. "You mean, like someone-told-a-joke laughing?"

"No," Abby said. "Like crazed-hyena-in-the-middle-of-the-night laughing."

"She was hysterical," explained Kristy. "Completely and totally hysterical."

"So what did that teacher - Mr. Rothman - do?" asked Shannon.

"He just said, 'Let's go, Liz,' and he led her out of the gym," I replied.

"I thought he was very sweet with her," said Mary Anne.

"Well, he blames himself," I explained. "But it's not really all his fault. From what I heard afterward, it sounds as if she were unbalanced to start with, and she'd been slowly becoming more and more disturbed over the years. She was completely obsessed with what had happened to her at that dance twenty-eight years ago. In fact, she's spent a lot of time in mental hospitals since then. That's where she went when she moved away from Stoneybrook."

"Wow," Shannon breathed. "What a story." She helped herself to a handful of M&Ms. "So was she the one who tried to ruin your dance?"

"Oh, didn't we tell you?" Abby asked. "She confessed to everything as Mr. Rothman was leading her out of the gym. She just kept babbling about all the things she'd done. Apparently she had flipped out when she discovered that SMS was planning another Mischief Night masquerade. She did her best to make sure the dance wouldn't happen, especially after she found out that Mr. Rothman had returned to SMS to teach."

"She was responsible for the lights going out in the auditorium that day," Kristy began, ticking things off on her fingers, "and for breaking those light bulbs, and cutting up the streamers - "

"And let's not forget that she ruined my posters," Claudia added, "and painted things on the gym walls."

"I know I'll never forget that dummy she hung from the basketball hoop," I said, shivering. "Talk about creepy!"

"So where is she now?" asked Shannon.

"Back in a hospital," Kristy said. "At least, that's what today's paper said. I hope someone there can help her."

"I just hope she never turns up at SMS again," said Mary Anne.

"So does Mr. Rothman," I added. "I saw him today in the hall, and he still looked ghost-white."

"Well, that might have been because of what the Mischief Knights did," said Kristy, leaning back in the director's chair. She grinned.

"Mischief Knights?" I asked. "I didn't know they were still causing trouble. What happened?" I couldn't believe I hadn't heard about it.

"They were pulling pranks all day," said Claudia. "It was as if they wanted everybody to know they were still active. They left their signature every time, too."

"Right," said Mary Anne. "Like, they piled candy corn in one of the trophy bowls in the display case, and left a note signed MK."

"And they put a Frankenstein mask in some girl's locker," added Claudia. "You should have heard her scream when she opened it!"

"What did they do to Mr. Rothman?" I asked.

"It was silly, really," said Kristy. "They just stuck one of those pink 'While You Were Ouf messages on his desk, with a note saying that Liz Connor had called."

"Hmmm. Not so funny, if you'd been through what he'd been through," I said.

"I guess," Kristy agreed. "But basically harmless. I think it's kind of fun having the Mischief Knights around. If Cary Retlin is involved, I hope his family doesn't move anytime soon. SMS can use a little lightening up, and I think the Mischief Knights are just the guys to do it."

"As long as the BSC doesn't end up on their bad side," I mused. "I have a feeling that might be dangerous."

"By the way, speaking of candy corn," said Claudia, "wasn't Halloween a gas?"

It had been fun. We had organized a group of sitters and kids, since several parents had called to ask us to take their kids trick-or-treating. Mary Anne, Claudia, Jessi, Mal, and I had taken a big group of kids around our neighborhood. (Kristy and Shannon took their younger brothers and sisters trick-or-treating in their neighborhood, with Abby's help.) Our group included all the Pike kids, plus Becca Ramsey, Charlotte, the Arnold twins, Matt and Haley Braddock, and a few other regular BSC clients.

We sitters wore our costumes from the night before. (Claudia's giant Twinkie costume was the kids' favorite, naturally.) But the hilarious thing was that each and every kid in our group was dressed as - guess what - a Ghost-buster! We had a small army of Ghostbusters, and all of them were outfitted with ray guns and collection units and detectors and ghost-busting tools of every description. Those kids ghostbusted every house within a ten-block radius. They came away with their collection units empty, but their treat bags full to bursting with Halloween candy.

"I hope that's it for Ghostbusters," said Jessi. "If I hear that song one more time, I might throw up!"

"I think Ghostbusters fever might be winding down," Mary Anne said. "I actually heard Carolyn tell Haley that she almost wished she'd dressed as a fairy tale character instead. That was after she saw Grace Blume walk by dressed as Snow White. Grace was out with her little cousins."

"Grace Blume!" I said, frowning. "Don't mention that name in front of me."

"Why not?" asked Mary Anne. "She's okay, as long as you keep her away from c.o.kie."

"That's it," I replied. "She and c.o.kie are like this again." I held up two fingers, crossed. "c.o.kie apologized for not trusting her, and Grace forgave her. And as soon as they started hanging out together again, they were up to their old tricks."

"What did they do?" asked Kristy.

"You won't believe this," said Claudia. I'd already told her about it, and she was furious.

"Well, you know that new art teacher, the one everybody likes so much? Ms. Dwyer?" I said. "She loved the decorations for the dance, and thought they were 'super-creative.' She wanted to know who had come up with the idea for them, because she has a special project .that she needs help with."

"That's great!" said Kristy. "So you'll be working with her."

I shook my head. "Not me," I said. "c.o.kie. She took full credit for the decorations."

"But she hated every idea the committee came up with," said Mal.

"Yup," I said. "But Ms. Dwyer doesn't know that. And c.o.kie convinced Grace to back her up on her lie. Grace supported everything c.o.kie said."

"Unbelievable. You really can't trust either one of them, can you?" asked Kristy.

"It's too bad," said Mary Anne. "I thought Grace was going to turn out okay. But I guess c.o.kie's influence is too strong."

"You know?" I said. "In a way, I really don't mind. Having c.o.kie and Grace plot against the BSC is just like old times. I mean, it's normal for us. And after all we've been through over the past couple of weeks, I'm happy things are back to normal again."

About the Author.

ANN MATTHEWS MARTIN was born on August 12, 1955. She grew up in Princeton, NJ, with her parents and her younger sister, Jane.

Although Ann used to be a teacher and then an editor of children's books, she's now a full-time writer. She gets the ideas for her books from many different places. Some are based on personal experiences. Others are based on childhood memories and feelings. Many are written about contemporary problems or events.

All of Ann's characters, even the members of the Baby-sitters Club, are made up. (So is Stoneybrook.) But many of her characters are based on real people. Sometimes Ann names tier characters after people she knows, other times she chooses names she likes.

In addition to the Baby-sitters Club books, Ann Martin has written many other books for children. Her favorite is Ten Kids, No Pets because she loves big families and she loves animals. Her favorite Baby-sitters Club book is Kristy's Big Day. (By the way, Kristy is her favorite baby-sitter!) Ann M. Martin now lives in New York. She has two cats, Mouse and Rosie (who's a boy, but that's a long story). Her hobbies are reading, sewing, and needlework - especially making clothes for children.