"Other mermaids have been losing their moon stones too?" Sirena questioned, her eyebrows raised in shock.

Ondina had gone back to Rita's house and told Sirena and Mimmi everything they Veridia had said. And then Rita had come back home, so Ondina had to explain everything again!

"Not losing, Veridia thinks they've been stolen," Ondina said, Twisted Mimmi's ring on her finger, checking the stone was still there. "Veridia thought if she made us stay on land it would keep our rings safe. And I ended up having mine stolen anyway!!"

"What could be going on?" Mimmi wondered.

All the mermaids turned to face Rita. When Rita was at mermaid school she was the top of her class.

Rita sighed. She rested her arms on the wooden gate next to the steps. "I have no idea. I've never experienced anything like this. I didn't think that the stones could fall out."

"So you're saying it could have been magic?" Sirena asked, looking at her own moon ring which was, thankfully, still in one piece.

"That sounds like the only possible solution," Rita sighed.

"Yeah, I spent all morning searching for Ondina's stone, and I couldn't find it anywhere. I even checked the café! David said he'd look out for it. But it's nowhere to be found!" Sirena notified everyone.

"I definitely had it when we got back to Rita's last night," Ondina remembered. "I used its magic to try make the cushion more comfortable. It didn't work."

Mimmi raised her hand to speak. "What I'm wondering about is... How did they managed to take the ring? We were in the grotto all night."

"The front door was locked, and so we're all the windows. Nothing seemed out of place this morning," Rita casted her mind back.

"So the only other possible was to enter the grotto is...the underwater entrance?" Mimmi said. This got everyone's attention.

"Who do we know that knows about the pool entrance?" Sirena asked.

"Zac and Evie," Ondina said.

"That's it, isn't it?" Sirena asked. "I can't think of anyone else. But they wouldn't take our moon stones, would they?

"Evie has a moon ring of her own," Mimmi commented.

"We should see if Evie's moon stone is still safe," Sirena said, and she stood up.

Just then Poseidon, Rita's pet cat entered the room. He sleekly made his way down the stairs and onto the sofa next to Sirena.

"Hey Poseidon," Sirena immediately sat down again and Poseidon climbed onto her lap.

"Urgh, how can you do that!?" Ondina asked, disgusted. She didn't like cats too much. At one point Sirena didn't either. But she got used to Poseidon, and they had become good friends.

"I have to admit, cats are a bit strange," Mimmi said, turning her body so she was further away from Poseidon. She didn't really like cats either.

"Poseidon's lovely," Sirena said, stroking the white fluffy cat.

"It's weird," Ondina complained.

"Girls," Rita snapped her fingers. "You're getting off subject."

"Right," Mimmi stood up. "I'll go see if Evie has still got her stone."

"You'll have to be quick," Rita said. "She, Zac and the others have got a practice exam coming up in a few days. They need to revise."

"I won't be too long," Mimmi promised.

"And maybe you'd better go see Zac too?" Ondina suggested.

"Why?" Sirena asked.

"Because he might be taking the moon stones!" Ondina said quickly.

Mimmi narrowed her eyebrows. "He wouldn't do that."

"Why not?" Ondina stood up. "You don't need to defend your brother all the time!"

"What do you have against him!?" Mimmi shouted angrily. "Just because he's a merman, is that it?"

"Because he tried to activate the merman chamber, he tried to take control over the trident! Zac's choices in the past haven't always been the greatest," Ondina yelled back.

"Girls!!!!" Rita shouted, and this make all three mermaids jump. Poseidon purred.

"There is no need to fight," Rita said. "Ondina's idea might be true, but that doesn't mean it was definitely, Zac who took the stones."

"I'm going," Mimmi sighed, angrily flying up the stairs and stalking out of the grotto. They heard the sound of the bookshelf sliding open, and then they heard it bang shut.

"There was no need to say that," Sirena said to Ondina.

"It was a suggestion!" Ondina sighed, sitting down on the floor and crossing her legs.

"There was still no need to say it," Sirena shook her head, slightly disappointed. "You know that Mimmi gets easily hurt."

Ondina looked down at Mimmi's ring, which she was still wearing. She sighed once more. "I know..."

***

An angry Mimmi made her way to Evie's house. She was so furious with Ondina. Mimmi barely ever got cross with people, she usually kept all her thoughts, and anger to herself. and then when someone finally said something she didn't like, all her anger seemed to tumble out of her all at once, and she barely had any control over it.

Mimmi would have swam to Evie's house, but she just felt like she needed a bit of fresh air. So she walked.

Mimmi got to Evie's house and knocked on the door. She waited until the door opened.

"Hello," Evie's dad opened the door.

"Hello, is Evie in?" Mimmi asked.

"She most certainly is," Evie's dad smiled. He held the door open and Mimmi entered.

Evie was sat at the table, a text book opened in front of her, and a notebook too, where she was writing down notes in what she would need to revise for the test.

"Mimmi!" Evie smiled, putting down her pencil and standing up. "Is everything okay?"

"I'll leave you girls too it," Evie's dad said, walking into the other room with a boating magazine in his hand.

"Everything's fine," Mimmi responded when Evie's dad had left the room. "Well, actually... It's not. Do you still have your moon ring?"

Evie smiled and held out her hand. Her moon ring was on her index finger, and the stone was still there. "It's right here. Why?" Evie looked at Mimmi's hand. "Where's your ring?"

"Ondina has it," Mimmi sighed.

"Why does Ondina have it?"

"Because the stone from her ring has gone missing, and we believe it's been stolen."

Evie's eyes widened. "Stolen!?"

"Yes, and I needed to make sure your ring is safe."

"Who would take them?" Evie asked.

"I'm not sure, but Veridia - head of the Mermaid Council - has given me, Sirena and India the job of finding them." And Mimmi quickly explained to Evie everything Ondina had told her.

"I'd love to help find who ever is taking the stones," Evie said as soon as Mimmi had finished. "And I'm sure Zac would be more then willing to help."

Mimmi nodded. "Thank you, Evie. Shall wet go see Zac?"

Evie nodded. "Let me pack my revision away, and I'll go get Zac, can we meet you, Sirena and Ondina at the café later?"

Mimmi nodded. "That shouldn't be a problem. I'll see you later then?"

"Definitely," Evie nodded back, closing her books and putting them into a pile.

***

Evie went to go tell Zac everything Mimmi had told her. They were in Zac's bungalow, which was a large shed in his parents garden. It was where his room was located.

"Why would anyone do that?" Zac asked, putting his own revision book down.

"I have no idea, but we're meeting the other mermaids at the Ocean Café."

"We had better get down there." Zac stood up and brought out his phone. "Should I get Cam to come?"

"Cameron is probably already at the café," Evie replied. "Either eating loads of food, or helping Carly."

Zac nodded. "Fair point." He put his phone into his pocket. But then it vibrated, and he pulled it out again.

"Who is it?" Evie asked curiously.

"It's a house number, but it's unknown," Zac replied.

"Don't answer it!" Evie said, horrified as Zac's thumb made its way to the green 'answer' button.

"It will only take a minute," Zac said. He answered the call and held his phone to his ear. "Hello?" He asked.

Evie folded her arms and watched.

"Oh, hi Ondina," Zac pointed to the phone and looked at Evie.

"Loud speaker," Evie whispered.

Zac pressed at button on his phone and held it out. "What's up?"

"We need to talk to you, it's really important," Ondina's voice came from the phone. Then there was a pause. "Sirena? Am I holding this thing the right was up?" They heard Ondina say.

Zac gave a little laugh. "We can hear you fine, Ondina."

"Good, can we come over to yours?" Ondina asked.

"Mimmi suggested we meet at the café," Evie called.

"That could always work," Ondina replied. "We have a problem."

"About the moon stones?" Zac asked. "Yeah, we know."

"You already know?" Ondia asked.

"Yeah, Mimmi told Evie, and Evie told me," Zac responded.

"... Right..." Ondina responded, but she didn't sound too sure. "We'll meet you there then?"

"Definitely," Zac said.

"Okay bye," Ondina said.

"Bye," Zac said back.

"I hate these stupid things," Ondina sighed.

"Ondina we can still hear you," Evie said.

"WHAT!? How to I turn this thing off!? I'll have to zap it."

"I'll end the call," Zac said. "I'll see you at the café."

And he ended the phone call.

"Let's go." Evie opened the door.

Zac grabbed his keys and nodded.

Five seconds later, they were out of the door, in the water, and swimming to the Ocean Café.