“I guess so,” I said.

  I knew Alexander had a good point. I loved Dr. D., and I didn’t want to spoil his big discovery.

  But, still, the mermaid shouldn’t have to suffer for science, I thought.

  “Come on, Billy,” Alexander said, leading me below deck. “I promised you I’d show you how the sonar probes work, didn’t I? Let’s go down to the lab, and I’ll give you a demonstration.”

  As we started to climb below, I took one last glance back at the mermaid. She was still slumped forlornly at the bottom of the tank. Her head was lowered, her blond hair floating limply above it like seaweed.

  The sonar probes weren’t as interesting as I thought they’d be. All they did was beep whenever the Cassandra was in danger of running ashore.

  I guess Alexander could tell my mind was not on the sonar probes. “Want some lunch?” he asked me.

  Uh-oh. Lunch. I was hungry. But not for spicy chicken salad.

  I hesitated. “Well, I had a big breakfast….”

  “I’ll whip up something special,” Alexander offered. “We can have a picnic up on deck with the mermaid. Come on.”

  What could I do? I followed him to the kitchen.

  He opened the small refrigerator and pulled out a bowl.

  “This has been marinating all morning,” he said.

  I looked into the bowl. It was full of thin strips of something white and rubbery-looking. They floated in an oily, dark gray liquid.

  Whatever it was, I knew I couldn’t eat it.

  “It’s marinated squid,” said Alexander. “I added some squid ink for extra flavor. That’s what makes it gray.”

  “Yum,” I said, rolling my eyes. “I haven’t had squid ink in days!”

  “Don’t be so sarcastic. You might be surprised,” Alexander replied. He handed me the bowl. “Take this up on deck. I’ll bring some bread and iced tea.”

  I carried the bowl of squid up and set it down near the mermaid’s tank.

  “How are you doing, Mermaid?” I asked her.

  She flipped her tail a little. Then she opened and closed her mouth, as if she were chewing.

  “Hey,” I said. “You are hungry, aren’t you?”

  She kept making that chewing motion. I glanced down at the bowl of squid.

  Who knows? I thought. This might be just what she’d like.

  I stood on a rail and unlatched the top of the tank. Then I dropped in a piece of the rubbery squid.

  The mermaid leaped toward it and caught it in her mouth.

  She chewed, then smiled.

  She liked it!

  I gave her some more. She ate it.

  I rubbed my stomach. “Do you like it?” I asked her. I nodded yes.

  She smiled again. Then she nodded yes.

  She understood me!

  “What are you doing, Billy?” Alexander asked. He had come up on deck carrying two plates and a loaf of bread.

  “Alexander, look!” I cried. “We communicated!”

  I dropped another piece of squid into the tank. She ate it. Then she nodded yes.

  “That means she likes it!” I said.

  “Wow,” murmured Alexander. He put down the plates and picked up his notebook. He scribbled some notes.

  “Isn’t that way cool?” I demanded. “I’m a scientist, too—aren’t I, Alexander?”

  He nodded, but kept writing.

  “I mean, I’m the first person on Earth to communicate with a mermaid—right?” I insisted.

  “If she stays with us long enough, you might be able to talk to her in sign language,” he said. “Just think of the things we could learn!”

  He spoke aloud as he wrote, “Likes to eat squid.” Then he put down his pencil and said, “Hey, wait! That’s our lunch!”

  Uh-oh, I thought. I hope his feelings aren’t hurt.

  He looked at me. He looked at the bowl. He looked at the mermaid.

  Then he started laughing.

  “At least somebody around here likes my cooking!” he exclaimed.

  About an hour later, Dr. D. returned with the groceries and supplies. Luckily he had bought plenty of seafood in Santa Anita. We fed some of it to the mermaid for supper. While she ate, Dr. D. checked the readings on the meters Alexander had set up in the tank.

  “Interesting,” Dr. D. commented. “She sends out sonar signals through the water. Just as whales do.”

  “What does that mean?” asked Sheena.

  “It means there are probably other mermaids like her,” said Dr. D. “She must be trying to contact them with underwater sounds.”

  Poor mermaid, I thought. She’s calling to her friends. She wants to be rescued.

  I went to my cabin after supper and stared out of the little porthole.

  An orange sun sank slowly into the purple horizon. A wide carpet of gold light shimmered in the rolling ocean waters. A cool breeze blew in through the porthole.

  I watched the sun drop into the ocean. The sky immediately darkened, as if someone had turned off a lamp.

  The mermaid is up there all alone, I thought. She must be so frightened. A prisoner. Trapped in a fish tank in the dark.

  The door to my cabin suddenly burst open. Sheena bounded in, panting, her eyes wide.

  “Sheena!” I scolded angrily. “How many times do I have to tell you to knock first?”

  She ignored me. “But, Billy!” she gasped. “She’s escaped! The mermaid escaped!”

  18

  I leaped off my bed, my heart pounding.

  “She’s not there!” Sheena cried. “She’s not in her tank!”

  I darted out of the cabin, up the hatch, and out on deck.

  Part of me hoped she really had escaped to freedom. But part of me wished she could stay forever—and make my uncle the most famous scientist in the world and me the most famous nephew of a scientist!

  Please let her be okay, I thought.

  Up on deck, my eyes adjusted to the evening darkness. Tiny lights glowed all around the edge of the boat.

  I squinted across the deck at the giant fish tank.

  I ran so fast, I nearly toppled overboard. Sheena was right behind me.

  “Hey—!” I cried out when I saw the mermaid floating listlessly in the water, her green tail shimmering faintly in the fading light.

  It took me a few seconds to realize that Sheena was laughing. “Gotcha!” she shouted gleefully. “Gotcha again, Billy!”

  I groaned long and loud. Another one of Sheena’s stupid tricks.

  “Good one, Sheena,” I said bitterly. “Very clever.”

  “You’re just mad because I fooled you again. You’re so easy to trick.”

  The mermaid raised her eyes to me, and a faint smile formed on her pale lips. “Looorrrooo, looorrrooo,” she cooed at me.

  “She really is pretty,” Sheena said.

  The mermaid is hoping I’ll let her go now, I thought. Maybe I should….

  Sheena could help me, I decided. It would be easier with two of us.

  But would my sister cooperate? “Sheena—”I began.

  I heard footsteps behind us. “Hey, kids.” It was Dr. D. “It’s almost bedtime,” he called. “Ready to go below?”

  “We never go to bed this early at home,” Sheena whined.

  “Maybe not. But I bet you don’t get up so early at home, either. Do you?”

  Sheena shook her head. We all stood at the tank and watched the mermaid in silence. She gave her tail a little flick and settled back down at the bottom of the tank.

  “Don’t worry about her,” Dr. D. said. “I’ll check on her during the night to make sure she’s all right.”

  The mermaid pressed her tiny hands against the glass wall of the tank. Her eyes pleaded with us, pleaded with us to set her free.

  “She’ll feel better once she gets to Marina Zoo,” Dr. D. said. “They’re building a special lagoon just for her, with a reef and everything. It’ll be exactly like the lagoon off Ilandra. She’ll be free to swim and play. She?
??ll feel at home.”

  I hope so, I thought. But I didn’t feel so sure.

  The Cassandra rocked gently on the waves that night, but I couldn’t fall asleep.

  I lay on my bunk, staring at the ceiling. A pale beam of moonlight fell through the porthole and across my face. I couldn’t stop thinking about the mermaid.

  I tried to imagine what it would feel like to be trapped in a glass tank for a whole day. It probably wouldn’t be that different from being trapped in this tiny cabin, I thought, glancing around. My cabin was about as big as a closet.

  It would be terrible, I thought, fiddling with the collar of my pajama top. I pushed open the porthole to let in more air.

  The fish tank might not even be the worst of it, I figured. I know Dr. D. cares about the mermaid. I know he’d never hurt her.

  But what will happen to her when the zoo people take her away? Who will look out for her?

  Sure, they’re building a fancy fake lagoon. But it won’t be the same as the real lagoon. And there will be people around, staring at her all the time. They’ll probably expect her to perform tricks or something; maybe jump through hoops like a trained seal.

  They’ll probably put her in TV commercials, too. And TV shows and movies.

  She’ll be a prisoner. A lonely prisoner for the rest of her life.

  This is all my fault. How could I let this happen?

  I have to do something, I decided. I can’t let them take her.

  Just then I thought I heard something—a low hum. I lay very still and listened. At first I thought it was the mermaid. But I quickly realized it was a motor.

  I heard it chugging softly, from a distance. But slowly the sound moved closer.

  A boat.

  I sat up and peered out of the porthole. A large boat pulled quietly up beside the Cassandra.

  Who was it? The zoo people?

  In the middle of the night?

  No. It wasn’t the same boat. This boat was much bigger.

  As I peered out the small porthole, I saw two dark figures quietly slip on board the Cassandra. Then two more.

  My heart began to race. Who are these people? I wondered. What are they doing?

  What should I do?

  Should I sneak up and spy on them? What if they see me?

  Then I heard more strange noises.

  A thud. A muffled cry of pain.

  It came from the deck.

  The deck. Where the mermaid was trapped helplessly in her tank.

  Oh, no! I thought, feeling a chill of panic. They’re hurting the mermaid!

  19

  I charged up to the deck. Sheena ran right behind me.

  Stumbling over a tow rope, I grabbed the rail to steady myself. Then I darted blindly to the fish tank.

  The mermaid huddled at the bottom of the tank, her arms wrapped protectively around herself.

  I saw four men standing tensely near the tank. All four were dressed in black. They had black masks pulled over their faces.

  One of the men held a small club in his hand.

  And a body lay sprawled on the deck, face down.

  Dr. D.!

  Sheena screamed and ran to our uncle. She knelt beside him. “They hit him on the head!” she cried. “They knocked him out!”

  I gasped. “Who are you?” I demanded. “What are you doing on our boat?”

  The four men ignored me.

  Two of them unfolded a heavy rope net and spread it over the fish tank. Then they let it fall into the tank, draping it over the mermaid.

  “Stop it!” I yelled. “What are you doing?”

  “Be quiet, kid,” the man with the club muttered. He raised the club menacingly.

  I watched helplessly as they tightened the net around the mermaid.

  They were kidnapping her!

  “Eeeee! EEEEEeeee!” she squealed in terror and started to thrash her arms, struggling to free herself from the heavy net.

  “Stop it! Leave her alone!” I cried.

  One of the men gave a low laugh. The other three still ignored me.

  Sheena was bent over Dr. D., frantically trying to wake him up. I ran to the hatch and shouted down into the cabin, “Alexander! Alexander! Help!”

  Alexander was big and strong—maybe strong enough to stop these men.

  I ran back to the tank. The mermaid was trapped in the net. All four men worked to lift her out of the tank. She squirmed and fought with all her strength.

  “EEEEEE!” she screamed. The high-pitched squeal hurt my ears.

  “Can’t you get her to shut up?” one of the men cried angrily.

  “Just load her on board,” the one with the club replied sharply.

  “Stop!” I yelled. “You can’t do that!”

  Then I totally lost it.

  Without thinking, I dove toward the four of them. I don’t know what I planned to do. I just knew I had to stop them.

  One of them pushed me away easily with one hand. “Stay away—or you’ll get hurt,” he muttered.

  “Let her go! Let the mermaid go!” I cried frantically.

  “Forget about the mermaid,” said the man. “You’ll never see her again.”

  I grabbed the rail. My heart was pounding in my chest. I gasped for breath.

  I couldn’t stand the mermaid’s terrified screams.

  I couldn’t let them take her—not without a fight.

  She had saved my life once. Now it was my turn to save hers.

  But what could I do?

  They had lifted the mermaid out of the tank. Three men held her in the net.

  She squirmed and thrashed like crazy, splashing water all over the deck.

  I’ll tackle them, I thought. I’ll knock them over. Then I’ll push the mermaid into the ocean and she can swim away to safety.

  Lowering my head like a football player, I took a deep breath and ran right at them.

  20

  “Billy—stop!” Sheena screamed.

  I crashed into one of the men holding the net, butting him hard in the stomach with my head.

  To my dismay, the man hardly moved.

  He grabbed me with his free hand, lifted me up off the deck, and heaved me into the fish tank.

  I splashed into the warm water and came up, choking and sputtering.

  Through the glass, I watched the men toss the mermaid aboard their boat. They were getting away!

  I tried to scramble out of the tank, but it was too tall. I kept slipping down the wet glass, unable to reach the top.

  I knew there was only one person who could stop the masked men now. Alexander.

  Where was he? Hadn’t he heard all the noise?

  “ALEXANDER!” I shouted as loud as I could. But my voice was muffled by the glass walls of the tank.

  Then, finally, he appeared on the deck. I saw his big blond head and muscular body moving toward me. At last!

  “Alexander!” I cried, scrambling to stay afloat in the tank. “Stop them!”

  I could hear the motor of the other boat begin to rumble. One by one, the masked men lowered themselves off our boat.

  Three of them had left the Cassandra. Only one remained on deck.

  Through the glass I watched Alexander run up to him and grab his shoulder.

  Yes! I thought. Get him, Alexander! Get him!

  I’d never seen Alexander hit anyone before. But I knew he could do it if he had to.

  But Alexander didn’t hit the masked man. Instead, he asked, “Is the mermaid safely on board?”

  The masked man nodded.

  “Good,” Alexander replied. “And have you got the money for me?”

  “Got it.”

  “All right,” Alexander murmured. “Let’s get out of here!”

  21

  I nearly choked on a mouthful of water.

  I just couldn’t believe that Alexander was working with the masked men. He had seemed like such a good guy.

  But I knew now that he had arranged the whole thing. He had to be the one who ha
d told them the mermaid was on board our boat.

  “Alexander,” I cried, “how could you?”

  He stared at me through the glass. “Hey, Billy, it’s just business,” he said with a shrug. “The zoo was going to pay a million dollars for the mermaid. But my new bosses will pay twenty million!” A thin smile crossed his face. “You know arithmetic, Billy. Which would you choose?”

  “You rat!” I shouted. I wanted to punch him. I struggled to get out of the tank. All I managed to do was splash a lot and get water up my nose.

  Alexander followed the masked man to his boat. I pounded helplessly on the glass tank.

  Then I saw Sheena stand up. Lowering my gaze to the deck, I saw that Dr. D. was moving.

  Alexander didn’t seem to notice. He stepped over Dr. D.’s body. He didn’t even care that Dr. D. could have been hurt badly.

  I watched my uncle reach up and grab Alexander by the ankle.

  “Whoa!” Alexander tripped and fell hard onto his elbows and his knees.

  Sheena screamed and backed up to the rail.

  Maybe there’s still hope, I thought, my heart beating faster. Maybe they won’t get away after all.

  Alexander sat up, dazed, rubbing one elbow. “Get them!” he shouted down to the masked men.

  Two of the men climbed back aboard the Cassandra and grabbed Dr. D. Sheena ran at them, flailing at them with her puny little fists.

  Of course that didn’t do any good. The third masked man grabbed her arms and pinned them behind her back.

  “Kick him, Sheena!” I yelled through the glass.

  She tried to kick the man who held her, but he just tightened his grip. She couldn’t move.

  “Let them go!” I screamed desperately.

  “What should we do with them?” asked one of the men.

  “Whatever you do, do it quickly,” said Alexander. “We’ve got to get out of here.”

  The man who held Sheena glanced in at me. I was frantically treading water, trying to stay above the surface.