Fang Harbor is always a busy place. Weekdays after school are no exception.

Every minute of every day, ships loaded with cargo sail in and out of the large underground port. Nestled in the safety of a giant cave, Fang Harbor has only one exit to the outside world—the Mouth. The top of the wide cave opening on the far side of the water is lined with jagged javelins of rock. These sharp rocks look like teeth and are what gave the harbor its name.

Beyond the Mouth lie the open sea and the surface world. I’ve always wanted to know more about the monsters living outside the mountain. But there are enough mysteries under this rock to keep me busy for now.

All around me, trucks, cranes and armies of dock workers scrambled to unload crates packed with fruits, vegetables, furniture, toys and anything else needed inside the mountain. Dozens of container ships would arrive that day, fully loaded. They’d drop their cargo and sail out, hauling minerals, mushrooms, barrels of valuable slick and other treasures the mountain had to offer.

Tank and I sat under the statue of Tiberious the Brave, the founding ogre of Slick City. He didn’t actually find the place. We goblins lived along these beaches for centuries before Tiberious showed up. The ogres won’t tell you that part of the story. They like to take all the credit themselves. There aren’t any statues for the goblin tribesmen who showed Tiberious how to turn slick into fuel. But goblins used the goopy black stuff under the sand to light their lamps for years before the ogres came along and pumped it out of the ground. Now the stuff keeps the entire Rockfall Mountain running. From gadgets to cars, slick is the stuff that makes it happen. And goblins were the first to use it. You won’t have much luck finding that in Mr. Mantle’s history books.

But then there’s Mr. Snag. He’s an ogre, and I’m working to prove he’s innocent.

Old Tiberious’s hairy stone feet made a good spot to sit and wait. We weren’t alone. A pair of teenage goblins sat against the statue’s other leg. They had their heads together, sharing a pair of headphones. They bopped their heads like yo-yos to some song I couldn’t hear.

Teenagers. Who gets them? Not this detective.

For me, the best part of the harbor was the monster-watching. I’d sit with my notebook and create stories about the monsters who passed by. Tank loved watching the ships chug their way slowly through the murky water. She had seawater in her bones, just like the rest of her family.

I wasn’t the only one unimpressed by Aleetha’s sudden appearance. The goblin teens gave her a wary look and moved to the far side of the harbor. Aleetha’s purple robes stood out against the brown rocks around us. Only students from the Shadow Tower wore robes of that color. Passing monsters crossed to the far side of the harbor path as they neared us. No one wanted to get close to the mysterious elf or her magic. Maybe arranging to meet Aleetha in public wasn’t such a good idea.

“Sorry for startling you. It’s just so much fun scaring the brave detectives of Gravelmuck Elementary.” Aleetha’s eyes twinkled. She wasn’t bothered by the stares from other monsters. Maybe they taught her that at mage school.

“We don’t have time for games,” I grumbled. “Mr. Snag is going to court tomorrow. The judge will decide if he’s responsible for letting the slimes out and damaging the school.”

“And you don’t think he is?” Aleetha said.

“It just doesn’t add up,” Tank said. “Mr. Snag loved his job and he loved his slimes. There’s no reason why he would let them do all that damage.”

“And there’s all that weird stuff happening at our school,” I said.

“What weird stuff?”

“This weird stuff.” Tank handed her camera to Aleetha.

The elf ’s brow furrowed as she watched Tank’s video from the equipment room.

It was a mess of red eyes, blue skin and flying soccer balls. You couldn’t make out what the creature looked like, but it did prove that we hadn’t caused all the damage. When we showed the video to Principal Weaver, it saved us from a year’s worth of detention. She didn’t seem too concerned that there were mysterious red-eyed creatures hiding in the equipment room. Who knows what goes on in the mind of a principal?

“Hard to say what that thing is,” Aleetha said when she finished watching the video. She handed the camera back to Tank. “It’s moving so quickly, and all we see are its shadows. Could be an imp.”

Tank moaned. “Oh, no, not imps! Our neighbor’s cave was infested with those little critters last summer. It was a mess.”

“They get everywhere,” Aleetha said. “They chew through wires, burst pipes and much worse.”

“Yeah, but would they cause the whole school to shake?” I said.

“No, but this stuff could.” Aleetha held up a small ball of soft putty.

“Is that play putty?” Tank asked. “The twins love that stuff.”

“Then they would really like this.” Aleetha walked toward a set of stairs that led to the water. “Follow me.”

She stopped at a quiet spot on the beach.

She pushed her thumb into the putty to make a hole.

“Hold this.”

She handed me the putty ball and pulled a little cloth pouch from her bag. She poured the purple powder into the tiny hole.

“Watch what happens when we add that purple powder you found.”

Aleetha took the putty ball back. She closed up the hole so that the powder was completely covered. Then she put the ball on the sand near the water.

She grinned as she walked back to us. “Ready?”

“Are you going to turn it into an imp?” I asked.

“No, but I’m tempted to turn you into one.”

I stopped with the lame jokes. It’s never good to make a wizard angry. Even a wizard-in-training.

“Watch.”

She stared at the ball. In a quiet voice, she said words in a language no monster outside of the Shadow Tower would understand.

“The purple powder is an explosive,” I said.

“But there was no sound,” Tank said. She moved to where the ball had been only a moment before. Now there was a crater in the sand. “No pop or bang or anything. It was completely quiet.”

“Exactly.” Aleetha grinned. “I played with it in the lab at school. It’s an explosive that’s been filled with magic to take away all the noise.”

“Perfect for blowing stuff up without anyone noticing,” Tank said.

She was right. Around us, the harbor continued to bustle with activity. Trolls and ogres sauntered along the docks. Boats moved around the piers. It was as if nothing had happened.

“Why blow something up if you can’t make it go boom?” I said. “The noise is the best part.”

“You’ll have to ask the monsters using this powder.”

“Monsters can’t use magic,” I said.

“Monsters that live up here near the surface can’t use magic,” Aleetha said. “But there are beasts from the Dark Depths that can tap into the forces of magic.”

“We found the powder in our school.” Tank tugged her spiky hair with worry. “That means somebody at Gravelmuck is messing with monsters from the Depths?”

“Another reason for you two to drop this case.” Aleetha looked hard at both of us. “Trust me, you do not want to mess with creatures from that deep under the mountain.”

The air behind her shimmered with a yellow glow.

“Time to go. I’m late for my transmutation class.” Aleetha stepped into the yellow light. She turned to us. The teasing was gone from her voice. “Be very careful with this one. Okay?”

She stepped into the glowing doorway and vanished.

We didn’t say much on the walk home. Both of us were deep in our own thoughts. I couldn’t shake the feeling that this mystery was growing too big for a pair of fourth-grade detectives.

Who at our school would have contact with monsters from the Dark Depths? That realm was serious business. The Depths was not a place you went on summer vacation. Demons and dragons lived down there. Any monster with half a tail knew not to mess with monsters from the Depths. And now someone at Gravelmuck Elementary was doing just that.

And what was the deal with the magic powder? It made things go boom without any noise. Why would anyone need that at our school? What did it have to do with the escaped slimes? More questions to add to the pile cluttering up my brain.

Don’t get me wrong—I like questions. It’s what keeps me in the detective game. But every once in a while, a case comes along that pushes even my limits. Where were the slimes? Did Principal Weaver let them escape so she could get rid of Mr. Snag? Why was a garbage truck racing straight for us again?