“Is she still in there?” Emma said worriedly. “Because if she is, I think we should, like, go.”

  Nancy shook her head. “No ghosts. No humans, either.”

  After a moment Nancy began circling around to the back of the cottage. The others followed, with Tessie videotaping the whole time. There were a couple of smaller windows that Nancy peered through too. But she couldn’t see anything interesting through those, either.

  She sighed in frustration. Whatever ghost or pretend ghost Michaela and Emma had seen before had disappeared.

  “Can we go now? Puh-leeease? I’m soooooo bored!” Amanda begged when they’d reached the front of the cottage again.

  Bess nodded. “I agree with Amanda. There’s nothing here. I say we go back to the beach and build us some sandcastles!”

  Nancy was about to reply when something caught her eye. A beam of sun lit up a small, metal object on the ground near the doorway.

  She reached down to pick it up, brushing sand off of it. At first it looked like a gold dollar.

  But after taking a closer look, Nancy could see that it wasn’t a gold dollar at all. She turned it over in her hand. It looked old and tarnished. On one side was a picture of a mermaid. On the other side was a picture of a bus. Or was it a train?

  Nancy’s heart began racing. Could this be a clue to the ghost? Or rather, a clue to the person who was pretending to be the ghost?

  “Is this the nacho-cheese-flavored popcorn or the chili-spice-flavored popcorn?” Nancy asked.

  Bess peeked into the bowl. “That’s the nacho cheese. Try it, it’s yummy!”

  Nancy, Bess, and George were having a sleepover in their room at the Mermaid Inn with Tessie, Michaela, and Emma. The floor was covered with sleeping bags, pillows, backpacks, teddy bears, and yummy treats. The two cats, Marshmallow Fluff and Vanilla Cream, were curled up on one of the twin beds.

  Nancy was wearing her new favorite pajamas, which were sky blue with pink heart-shaped buttons. She grabbed a handful of the nacho-cheese-flavored popcorn and opened her mermaid notebook—the one Michaela had given her.

  “So now we have a new clue to add to our clues list,” Nancy said out loud. “The gold coin.”

  Tessie turned on her KidCam. “What do we think it is?” she asked the group.

  George looked thoughtful. “Well . . . it’s probably not money, since it doesn’t have a number on it. You know, like ‘one dollar’ or ‘fifty cents’ or whatever.”

  “I think it’s pirate treasure!” Michaela said, grinning. “It probably came from a chest full of coins and jewels and stuff.”

  “Yeah. Maybe it’s supervaluable,” Emma agreed.

  “Hmm. Maybe Rowena’s ghost is hiding a big stash of pirate treasure somewhere. Or maybe she left it for us, as a message,” Tessie guessed.

  “What kind of message?” Bess asked her.

  “I don’t know. It’s another piece of the mystery!” Tessie said. “And . . . cut! I need to take a popcorn break!”

  She set her KidCam down and reached for one of the bowls.

  Nancy wrote down some notes about the gold coin on the clues page. “I wonder if Julio and Henry could have dropped the coin by accident?” she mused. “They left the beach about the same time we got there. So they would have had enough time to get to Rowena’s cottage. They could have gone inside and pretended to be her when you guys were walking by,” she added, turning to Michaela and Emma.

  “No way,” Michaela said, shaking her head. “The ghost was definitely real, and she was definitely a girl—I mean, a woman. She had long hair!”

  “Julio or Henry could have been wearing a wig,” George said, giggling.

  Nancy giggled too. “Ha-ha, funny!”

  Tessie frowned. “You guys just don’t get it! We’re dealing with a real ghost, not a person! Besides, there’s no way Julio and Henry could have been in the attic last night, pretending to be a ghost and leaving that message on the wall!”

  “Hmm. That’s true,” Nancy agreed.

  The door swung open with a long, slow creeeeeeak.

  Bess gave a little shriek. “Who’s there?” she demanded.

  Amanda hopped into the doorway. She was dressed in green dinosaur pajamas, and she was dragging a yellow sleeping bag behind her. Nancy wondered how long she had been standing there, and what she’d overheard.

  “I’m ready for the sleepover!” Amanda announced cheerfully.

  “Amanda, you’re not invited to the sleepover. It’s just for the big girls,” Tessie snapped.

  Amanda pouted. “But I am a big girl!”

  There were footsteps in the hall, then Claire entered the room. “I’m sorry, girls. Amanda, sweetheart, come with me. You and I can have our own sleepover!”

  “But, Mommy, I want to have a sleepover with the big girls! They’re telling ghost stories!” Amanda insisted.

  “Oooh, spooky! I can read you a ghost story in your bed, okay? Come on, honey.” Claire took Amanda by the hand and led her away.

  “It’s not faaaair!” Nancy heard Amanda cry out.

  “Sorry about my sister. She’s just a baby,” Tessie apologized to everyone. “Okay, so, where were we?”

  The girls continued to discuss the case for a while. Michaela and Emma painted each other’s toenails glittery purple. Hannah came up with more snacks: cookies, cut-up watermelon, and mugs of hot chocolate. It was almost eleven o’clock when no one could keep their eyes open anymore. They arranged their sleeping bags side by side on the floor and promptly fell asleep.

  With a start, Nancy sat up in her sleeping bag. She glanced at the clock on the nightstand: 12:12 a.m.

  Nearby, Bess and George were fast asleep. So were Michaela and Emma. Tessie seemed to be stirring a little, though.

  Bump . . . bump . . . bump . . .

  Nancy gazed up at the ceiling. The noises were coming from the attic.

  Bump . . . bump . . . bump . . .

  “Nancy?” Tessie whispered from her sleeping bag. “Did you hear that?”

  “Yes, did you?” Nancy whispered back.

  Tessie nodded. “It’s the ghost. She’s back!”

  Something was making noises up in the attic. Nancy didn’t think it was a ghost. But it definitely sounded creepy.

  Nancy gestured for Tessie to follow her. The two of them stood up and tiptoed out of the room, leaving the other four girls asleep in their sleeping bags. They rushed down the hall to the door leading up to the attic. Once there, Tessie grabbed the flashlight from its hook and clicked it on.

  “Shhhh,” Tessie said, putting her finger on her lips. “We don’t want to scare the ghost away.”

  Nancy nodded and gave Tessie a thumbs-up sign. Someone was up there, ghost or no ghost.

  Tessie led the way up the stairs. The weird noises continued overhead: Bump . . . bump . . . bump.

  Nancy’s heart was racing. Who—or what—was making that sound?

  At the top of the stairs Tessie handed Nancy the flashlight and clicked on her KidCam, which she’d had tucked under her arm. “Who’s there?” Tessie demanded.

  Someone giggled. A very familiar someone.

  Tessie gasped. “Amanda? Is that you?” she called out.

  Amanda jumped out from behind a cardboard box.

  “Boo!” she cried out. “Were you scared? Was I so, so superscary?” She bounced a big orange ball on the floor. So that was what was making the sound.

  Nancy and Tessie exchanged a glance. “How long have you been up here?” Nancy asked Amanda.

  Amanda shrugged and plucked a dust bunny from her pajamas. “I don’t know. I couldn’t sleep.” She giggled again.

  “This isn’t funny, and you are in such big trouble,” Tessie scolded her.

  Nancy thought for a moment. “Amanda, were you up here last night? Pretending to be the ghost, I mean? And did you write ‘Help me’ on the wall?”

  Nancy started to point to the message on the wall. But she realized with a start that it was gone. There
was a big smudge mark where it used to be, as though someone had wiped it away. When did that happen? she wondered.

  Nancy heard footsteps coming up the stairs. A moment later Claire and Leo appeared.

  “What on earth are you girls doing up here?” Claire said, surprised.

  “It’s after midnight,” Leo added.

  “Mommy, Amanda was up here pretending to be a ghost, and it woke Nancy and me up,” Tessie blurted out. “Can you give her a time-out, like, right now?”

  “I don’t want a time-out!” Amanda protested. “It’s not fair, because the big girls are having a sleepover, and they’re solving a ghost mystery, and I’m not invited because they said I’m not a big girl! But I am a big girl! I’m six and a half!”

  Claire and Leo exchanged a glance. “What ghost mystery?” Claire asked Tessie.

  “Oh, it’s nothing! We’re just making up spooky-scary ghost stories, you know, ha-ha!” Tessie said quickly.

  “Okay, well . . . we’ll talk about this in the morning. Right now everyone needs to go back to bed,” Leo said firmly.

  As they all headed down the stairs, Nancy wondered: Why didn’t Tessie want her parents to know about their search for Rowena’s ghost?

  “Mmm, I love blueberry pancakes!” George said, digging in.

  “Me too.” Bess turned to Nancy and Hannah. “Do you guys want a bite? How are your banana-walnut pancakes?”

  “Almost as yummy as my dad’s!” Nancy said with a grin. Hannah laughed and nodded.

  It was Wednesday morning, and the four of them were having breakfast at a restaurant called the Seashell Café. The tables were painted different bright colors and decorated with seashells. Carson was back at the Mermaid Inn working, and Tessie and Amanda were at their violin lessons.

  Nancy took a sip of her orange juice. Then she opened up her mermaid notebook to the suspects page and picked up a pen. “So I think we should add Amanda to the suspect list,” she said, writing. She had already told George and Bess about last night’s incident—and Hannah, too. “That means we have three suspects now: Amanda, Julio, and Henry,” she added.

  Bess craned her neck to peer at the notebook. “But there’s no way Amanda could have written that message on the wall,” she pointed out. “It was in very neat letters. She’s way too young to write that nice. I mean, my writing’s really bad, and I’m, like, two years older than her.”

  “Plus, there’s no way Amanda could have been at Rowena’s cottage yesterday, scaring Michaela and Emma. She was with us on the beach,” George said.

  Nancy sighed and tapped her pen on the table. “I know. Amanda isn’t a perfect suspect. Neither is Julio or Henry. None of our suspects is perfect.”

  “That’s because our suspect or whatever is a ghost,” Bess insisted. “You guys need to stop thinking there are real people involved!”

  “I still vote for ‘real people,’” George said, raising her hand.

  “Me too. But which ones? We need to think of more suspects,” Nancy said.

  She flipped the notebook to the clues page. She had written down:

  Spooky noises coming from the attic (Monday night). And the words “Help me” written on the wall in block letters. (But then someone erased the message! Who? When?)

  Tessie’s video (from two weeks before we got to Cape Mermaid).

  The funny-looking gold coin.

  PLUS Mrs. Yamada (the librarian) thinks the ghost was in the library a bunch of times.

  PLUS Michaela and Emma told us they saw the ghost inside Rowena’s cottage while we were all at the beach (Tuesday).

  Hannah got up to go pay the check. Nancy’s gaze fell on the line about the gold coin.

  She reached into her backpack and pulled out the coin. It was stored inside a small plastic bag. The Clue Crew members often kept their clues in small plastic bags to keep them safe.

  “I wish we could figure out what this is,” Nancy said, setting the coin on the table. “Maybe it’s toy money, like for a board game?”

  “And what is that a picture of, anyway?” Bess said, pointing to the image on the coin. “A bus? A train? A space shuttle? George, what do you think?”

  But George didn’t respond. She was staring out the window.

  Bess tapped on her shoulder. “Um, George? A little help here? We have a mystery to solve!”

  George turned around. Her brown eyes were sparkling. “I think I just did!” she said excitedly.

  “What do you mean you solved the mystery?” Nancy said curiously.

  “Well, I didn’t solve the whole mystery,” George replied. “But I think I know what the picture on the gold coin is.”

  She pointed out the window of the restaurant. A blue-and-gold trolley car was rolling to a stop outside.

  Then George pointed to the gold coin. “This isn’t a picture of a bus or a train or a space shuttle. It’s a picture of a trolley!” she announced.

  “Oh, wow, you’re right!” Bess cried out.

  Hannah returned to the table, tucking her wallet into her purse. “What’s all the excitement, girls? What did I miss?”

  “Remember the gold coin we found outside Rowena’s cottage?” Nancy said. “George just figured out what the picture on it is. It’s a trolley!”

  Hannah bent down and squinted at the coin. “George is absolutely right! Which means that this coin is probably a trolley token.”

  Bess frowned. “A . . . what?”

  “A trolley token. Some trolleys take tokens instead of money,” Hannah explained. “Of course, these days, it’s usually—”

  Nancy jumped to her feet, not waiting for the rest of Hannah’s sentence. “I’ll be right back!” she announced. She grabbed the trolley token from the table and raced out to the sidewalk. The blue-and-gold trolley was still parked on the street as riders got on and off.

  Nancy went up to the driver. He had a bushy white beard and tiny wire-rimmed glasses. Out of the corner of her eye she saw George, Bess, and Hannah running out of the Seashell Café to catch up to her.

  “Excuse me, sir. Is this a trolley token?” Nancy asked the driver breathlessly. She held up the gold coin for him to see.

  The driver bent down to take a closer look. “Well, yes, this is a trolley token,” he said after a moment.

  Nancy grinned. “Yay!”

  “But hold up, young lady. This is a very old token. We haven’t used tokens like these in at least fifty years—not since I used to ride this trolley as a young boy,” the driver went on.

  Nancy’s face fell. “Oh.”

  “No, missy, you’re not likely to see these around Cape Mermaid anymore. They’re historical relics,” the driver continued. “But if you want to ride the trolley now, kids are free, as long as they’re with a—”

  “Historical relics?” Nancy cut in. She turned to George, Bess, and Hannah. “We’ve got to get over to the history museum right away!” she said.

  “Why are we here?” George asked Nancy when they reached the front door of the Cape Mermaid History Museum.

  “I know! I wasn’t done with my blueberry pancakes yet,” Bess complained.

  Nancy held up the trolley token. “The driver said this is a historical relic. The history museum is full of historical relics, right? So maybe Mrs. Bishop can help us figure out where this came from.”

  “Oh, I get it! And whoever the token belonged to may have dropped it by accident outside of Rowena’s cottage yesterday,” Bess said. “Nancy, you’re a genius!”

  Nancy beamed. “Thanks, Bess!”

  The four of them headed into the museum. Mrs. Bishop was at the front desk, poring over a catalog.

  She glanced up and frowned. “You’re Tessie Katz’s friends, aren’t you? Are you here to ask me more questions about your so-called ghost?” she said irritably.

  But before Nancy or her friends could answer, a man entered the lobby from an adjoining room. “Rowena, I need to get your signature on this contract.” He stopped when he saw the girls. “Oh, I’m so
sorry, you’re in the middle of something.”

  Nancy’s eyes widened.

  Did the man just call Mrs. Bishop “Rowena”?

  And then she remembered the “Family Tree” section of Rowena Ellison’s biography. According to it, Mrs. Ellison had three daughters. One of those daughters had named her own daughter Rowena.

  “Are you Rowena Ellison’s granddaughter?” Nancy asked Mrs. Bishop. “Is that why you’ve been pretending to be her ghost?”

  Mrs. Bishop stared at Nancy. “W-what did you say?” she said in a trembling voice.

  “Are you Mrs. Ellison’s granddaughter?” Nancy repeated.

  Mrs. Bishop turned to the man. “Franklin, I’ll look over that contract later. Can you give us a moment?” she asked him.

  “Yes, of course.” Franklin nodded and exited the lobby.

  Bess, George, and Hannah were all looking at Nancy with surprised expressions.

  “How did you know?” Bess asked Nancy.

  “Rowena isn’t a supercommon name,” Nancy explained. “Plus, I read in Mrs. Ellison’s biography that she had a granddaughter named Rowena.”

  Mrs. Bishop was silent for a moment.

  “Okay, yes, Rowena Ellison was my grandmother,” she admitted finally. “But I don’t know anything about this ghost business!” she declared.

  Nancy pulled the trolley token out of her pocket and showed it to Mrs. Bishop. “Is this yours?”

  Mrs. Bishop gasped. “Oh my goodness, where did you find this? I’ve been looking all over for it! We’re in the process of setting up a new transportation exhibit. I was carrying this trolley token around with me yesterday because I was going to take it over to the frame shop to have it mounted. But then it disappeared!”

  “We found it just outside of your grandma’s cottage,” Bess spoke up. “You must have dropped it there yesterday—”