“It does look a bit like an obelisk,” Henry said. “But now that we’re closer, I can see it’s definitely a pyramid.”

  “The sign says this is called the Pirámide de Mayo,” said Jessie. “The May Pyramid. This has got to be what the clue was describing.”

  “‘When was I built?’” Benny chimed in with his sentence.

  Jessie kept reading the sign. “It says it was erected in 1811. Should we try the code in the box?”

  They were all excited to open the box, but Henry paused. There were many people all around. If they opened the box, Anna or any of Mr. Ganert’s hired men would be able to steal it. As long as it was locked inside the box and the passcode was safe in their heads, it wasn’t likely that they would lose the artifact.

  “Let’s find a restaurant for lunch,” he said. “That way we can have some privacy while we figure this out.”

  Grandfather nodded. “I saw a nice-looking café up the street. I would love to try some Argentinian coffee.”

  “Let’s go!” said Benny. “I want to know what’s inside that box!”

  The café was within walking distance, so they took in more sights on their way. Downtown Buenos Aires was full of people, cars, and beautiful architecture. Every building had columns or finely carved eaves or a fancy balcony. Jessie practiced her Spanish by reading the signs in store windows and on tour buses.

  The café was right where Grandfather said it would be. Most of the customers were sitting outside on the patio, but Henry asked the hostess if they could have a booth inside where it was quiet. They ordered sandwiches and iced tea, and while they waited for their food, Benny wiggled his fingers energetically.

  “The code!” he said. “Let’s use the code to open the box! I want to see what’s inside!”

  “All right, all right.” Henry laughed. From the booth, he could see the whole café. He was sure there were no Argent spies sneaking around. Henry slid his camera case over to Benny. “Go for it.”

  Benny and Violet opened the camera case together and took out the locked Reddimus box. It was finally time to open it and find out what the last artifact was. Everyone watched as Benny found the keypad and entered the four-digit code.

  “One, eight, one, one,” he said as he pressed the numbers. The box unlocked with a satisfying click. Benny carefully opened the lid and looked inside.

  “What is it? What is it?” Violet asked eagerly.

  Benny frowned and turned the box so they all could see.

  “It’s—it’s—empty!” he cried.

  “Shoot!” Henry exclaimed with dismay. “You don’t think Anna Argent got into the box somehow, do you?”

  Jessie reached inside and felt around. “Wait a minute. I think there’s something in here,” she said. After fishing around with her fingers, she pulled out a small strip of paper.

  “Something’s written on it,” Violet said as Jessie put the paper on the table. “It’s just numbers!”

  “Hmm, not just numbers. Let me take a look,” said Henry, turning the note toward him. “See here? There are dots in the numbers. And there is an S after one of the numbers and a W after the other one. I think these are coordinates.”

  “Coordinates?” asked Benny.

  “Yes. They’re numbers that represent a place on the world map. See, there are two numbers. One is latitude, which measures a distance north and south. The other is longitude, which measures distance east and west. With both numbers, we can find one place. Jessie, will you get your laptop out? We can find out where the coordinates point using the Internet.”

  Jessie did as Henry suggested. Benny wrung his hands, trying not to be too upset.

  “Are you sure Anna didn’t steal the artifact?” he asked.

  “How could she have?” asked Henry. “She didn’t have the code. These coordinates must just be the next part of the clue.”

  Jessie booted up her laptop. “That’s different from all the other boxes, though. All the other boxes had the artifact right inside. I wonder why this time it’s different.”

  “And Trudy said it was urgent we deliver the artifact as soon as possible,” Violet reminded them. “Now the box is open, but we still don’t have the artifact! I hope we don’t run out of time.”

  Henry gave the paper with the coordinates to Jessie, who input them into an Internet map search.

  “Don’t worry,” Henry said. “Let’s find out where these coordinates lead and then go there right away. We’ve outsmarted the Argents all this time. There’s no reason to worry now.”

  Jessie had finished looking up the coordinates on the map. She turned the laptop so everyone could see.

  “Look here. It looks like the coordinates are pointing to a place just outside Buenos Aires. It’s not very far at all.”

  Henry smiled just as the waiter appeared with their food. “See, Benny? No need to worry.”

  “Phew!” Benny said. “I was worried we wouldn’t have a chance to eat!”

  Jessie laughed. “Don’t worry, Benny. We’ll always find time for meals.”

  After they ate, Grandfather called another taxi. There were so many taxis in downtown Buenos Aires that all he had to do was whistle as one drove by. The Aldens got inside, and Jessie asked the driver if he could use coordinates in his GPS. After a minute, the man had entered the numbers.

  “¡La reserva natural!” the driver exclaimed with a smile as he started to drive.

  “What did he say?” Benny asked.

  “I think he said that we’re going to a nature reserve,” Jessie replied. “The words are kind of similar in English, aren’t they? Nature reserve, la reserva natural?”

  “Is that like an animal sanctuary, like the ones in Australia?” Violet asked. “I hope it is. I really liked seeing the kangaroos and koalas.”

  “What kind of animals come from Argentina?” Benny asked.

  “Hmm,” said Grandfather. “I suppose we might find armadillos. Or capybaras! Those are like giant guinea pigs.”

  Benny laughed at the idea of a giant guinea pig.

  “I hope we find capybaras,” he said.

  “I hope we find armadillos!” Violet added. “What about you, Henry?”

  “Me?” Henry asked. He laughed. “I hope we find the Reddimus artifact we’re supposed to return!”

  The Orange Orchid

  The taxi driver dropped them off at the visitor center of the nature reserve. The reserve was very different from the busy city center of Buenos Aires. Instead of people and street music, there was only the sound of wind in the trees. Grandfather took a big breath and let it out with a content sigh.

  “What a beautiful sight!” he said. “Isn’t it surprising when a quiet place like this can be so close to a bustling place like the city? So, what’s next?”

  “Now that we’re here, we’ve got to find out what we’re looking for,” said Henry. “We might be looking for another clue, but we could also be looking for a person. Keep your eyes peeled for owls and purple uniforms.”

  They went into the visitor center. Inside, there were rows with glass cases of delicate plants and flowers. The cases were lit with artificial sunlight. Some had mist sprayers that fogged up the windowpanes. In front of the cases were little signs with information about each plant. Where the walls weren’t covered with plants and flowers, they were decorated with woven textiles in many colors and geometric patterns.

  “They’re so beautiful,” Violet said, peering at the flowers. Some were tall and wide, while others were small enough they might fit in the palm of her hand. Violet especially liked the flower called the Argentinian vervain, with dozens of tiny purple blossoms growing in fluffy clusters.

  While Violet, Benny, and Grandfather looked at the flowers in the cases, Jessie and Henry puzzled over Henry’s phone. He had found a phone app that allowed him to track their location on a map, just like the GPS in the taxi.

  “Hmm,” said Henry. “Even though we’re very close to the coordinates we were given, we’re not quite
there yet. It looks like our real destination is out in the nature reserve.”

  “All right!” cheered Benny, who was listening nearby. “Let’s go!”

  They walked through the visitor center and out a set of doors on the other side of the building. Outside, they found themselves on a wide dirt trail that twisted off into a lush forest. The air was alive with birdsong, and in the distance they could hear the burbling of water. It was peaceful and quiet. It reminded Jessie a little of the woods where they had found their boxcar. Jessie doubted there was a boxcar sitting out in the Argentinian nature reserve, but the woods still made her feel at home.

  “According to my phone, we should head this way,” said Henry, and down the trail they went. They passed under low-hanging tree branches and stepped over moss-covered logs. The sunset twinkled through the leaves and shone in bright spots on the path. Benny ducked when something buzzed out of the trees and crossed the path right in front of them.

  “Whoa!” he exclaimed. “Was that a giant bug?”

  “No, look!” Violet said, pointing. The dark green flying creature hovered just off the path. It was no bigger than a golf ball. “It’s not a bug…it’s a bird!”

  “Oh, a hummingbird!” said Grandfather. “Would you look at that.”

  “I’ve never seen a bird so small…or a bug so big,” Benny said. The hummingbird flitted back and forth, as if it were watching them. Its wings were moving so fast they were almost invisible. It chirped once then buzzed away into the trees.

  “We’re getting close,” said Henry. He hadn’t seen the hummingbird because his eyes were glued to the GPS on his phone. Jessie thought he looked very serious. She also knew how important it was that they find the Reddimus artifact quickly.

  They followed the trail through the forest. Even though it seemed like they were hiking deep into the woods, the trail was well kept. Every once in a while, they saw a sign or a map, so they were never worried about getting lost. The trail wound around huge trees and alongside a little creek. Benny and Violet saw three more hummingbirds flitting through the trees.

  After a while, the trail curved up a little hill covered with fallen leaves and overgrown with white and purple wildflowers. It was quite a hike, and they were all a little winded by the time they neared the top.

  “Oof, this is all the exercise I’ll need this year!” joked Grandfather.

  When they finally made it all the way up, they were surprised to find a small building with a glass roof. Three of the walls were made of glass too, and inside they could see the building was full of lush, green plants.

  “This is definitely the place the coordinates point to,” Henry said, catching his breath and putting away his phone. “Let’s see if anyone’s home.”

  They found a buzzer beside the door, and Henry rang it. Even though the walls were made of glass, the plants inside were so thick that it was difficult to see if anyone was inside. After a minute, Benny pointed when he saw something move inside. Someone was home after all! A blond man with a floppy hat and big glasses opened the door a crack and looked out at them. At first he didn’t seem interested in meeting any strangers, but then his eyes went from Henry to Jessie to Violet to Benny.

  “Four children…” he murmured to himself. “It could be them…”

  Benny waved. “Hi, are you a friend of owls?” he asked cheerfully.

  That was proof enough. The man opened the door all the way and let out a big sigh of relief.

  “Yes, it must be you after all. Oh, thank goodness you’re here,” he said. “I’ve been waiting. Come in. Come in. My name is Hector—Hector Vargas.”

  The inside of the glass house was filled with plants. It didn’t seem like the kind of house someone actually lived in. There were no beds or chairs in the single room. There was a sink, but it was full of plant pots and potting soil. A long metal table took up the middle of the room. It was covered in trays and pots of more plants. The glass ceiling let in the sunlight, so all the plants were green and happy. It smelled like leaves, flowers, and fresh dirt.

  “Welcome to my greenhouse,” said Hector. He glanced over his shoulder suddenly, as if he were nervous he’d made a mistake. “You are the Aldens, right?”

  “Yes,” said Henry. He introduced himself and his siblings. “And this is our grandfather. He’s helping us while we’re in Argentina, since we can’t drive.”

  “And because I am wonderful company,” added Grandfather with a wink.

  “Wonderful to meet you all!” Hector called over his shoulder as he walked sideways through the tall, potted palms and hanging ferns. “Sorry there’s nowhere to sit. Please wait here a moment. I’ve got something to give you.”

  As he moved farther away, Benny could see his clothes were spotted with potting soil, and there was even a leaf stuck to his shoulder. It almost looked like he was a plant disguised as a person.

  “Finally!” Henry whispered. “I wonder if the artifact is a flower.”

  “Maybe that’s why it wasn’t in the box,” Violet agreed. “Can you imagine? A poor flower stuck in that dark box this whole time! It probably would have withered up. No wonder there were only coordinates inside.”

  Hector came back with a clear glass box, and the Aldens could see they were right. Hector cleared a place on the center table and set the box down so they could all see the flower inside. It had long, green, oval leaves. A skinny green stalk grew up from the center of the leaves, and at the end of the stalk was an intricate, orange blossom.

  “Oh my gosh,” said Violet when she looked closely. “The flower looks like a monkey face!”

  Indeed, the orange blossom had a cluster of petals in the center that looked like the face of a monkey or a baboon. There were even two dark spots where the eyes would be, and a darker petal in the center that looked like a nose.

  Hector nodded. “Yes. It’s called a monkey orchid. It’s not a very creative name, I suppose, but it is definitely an accurate description.”

  “Wow! Is this the artifact we’re supposed to return?” asked Benny. “Is it rare or valuable?”

  Hector nodded.

  “Something someone might try to steal and sell for a lot of money?” Henry added.

  Hector nodded again.

  “Monkey orchids are somewhat common, but this is the only specimen I’ve ever seen that’s this color. They’re usually white and peach, or sometimes dark red…So this orange orchid is incredibly rare. It would fetch quite a sum if it were put to auction. Plant collectors can be quite willing to spend a lot of money, and the rarer, the better.”

  “Where should we take it?” asked Henry. “We’ll return it right away!”

  This time Hector shook his head. “I wish I could tell you! It’s not my orchid. I have known the Silvertons for a long time, so when I found this orchid on my greenhouse doorstep, I understood that I should take care of it until the Reddimus Society found out where it belonged. Oh, I should mention, the messenger left something else…I reckon it’s a clue to help you figure out where you should take it.”

  Hector picked up a knotty rope from the table next to him. He handed it to Henry, who held it out for the others to see. It was a thin piece of white cord with dozens of other strands tied to it. Some of the strands were wrapped with green, silver, or gold knots.

  “What is it?” Benny asked. “It looks like a piece of a sweater that came unraveled.”

  “There was only a simple note that came with it,” Hector said. “All it said was, ‘This khipu is the final key.’”

  “Khipu? Huh?” Henry repeated. “I’ve never heard of that before.”

  Violet touched the soft pieces of rope. “I think it’s pretty. It reminds me of the friendship bracelets I made in school with embroidery thread. But I still don’t know what it means,” she said.

  “Didn’t we see something like that in the building?” Benny wondered out loud.

  “I think you’re right,” said Grandfather. “Next to all the flower cases there were some old-
looking textiles with similar colors and patterns.”

  Hector rubbed his chin with his thumb in thought. “The visitor center wouldn’t be a bad place to start looking. I don’t think you’ll find any clues out here!”

  Benny looked at the monkey orchid in its glass case. It looked very breakable.

  “We have to carry it in that?” he asked.

  Hector nodded. “Yes, unfortunately. The monkey orchid is very delicate. It can’t survive extreme temperatures. And since it’s a tropical plant, it needs to stay inside this special container. If it’s exposed to air that’s too dry, it will become one sad little flower. I’m familiar with caring for orchids, as you can see from my greenhouse, but even I know that this plant needs to be with a specialist if it’s going to be happy.”

  The Alden children looked at the orange orchid. It looked like it was looking back at them with its funny little monkey face. It was beautiful but fragile and very rare. No wonder Trudy had been told that returning the orchid was urgent.

  “We’ll do it,” Henry said confidently. “Let’s go to the visitor center, figure out what this khipu rope means, and get this little flower back where it belongs!”

  A Knotty Puzzle

  The Aldens walked with Hector back to the visitor center. Just as Benny had thought, the textiles that decorated the plant cases had many of the same colors and patterns as the rope clue. The children took turns looking at each of the draped fabrics and comparing them to the knotted khipu.

  “We can assume the khipu is some sort of message,” Jessie began. “Either that, or it’s from the place where we’re returning the orchid.”

  “Look at this one,” Grandfather said, waving them over. He was looking at a tapestry that was done in red and gold. The tapestry was divided into six squares, and each square had a different number of birds woven into the design. The first square had only one bird, the second had two, and so on. Benny counted them.