As they rode the conveyor belt through the Mali entrance, it reminded Samantha of the moving sidewalk they’d ridden in Newark airport about a week earlier. The slidewalk quickly moved, however, into a space unlike anything she had ever seen before.

A huge room, the size of two football fields laid end to end, stretched out in front of them. The ceiling arched high above, with glowing panels that bathed everything in bright white light. Humming, swishing sounds filled the air. The floor was covered with conveyor belts.

“Slidewalks?” said Nipper.

Samantha nodded.

She quickly counted twenty conveyor belts, all moving at different speeds. The ten belts on the right—including the one they were on—moved away from the entrance. To the left, ten belts moved back toward the ringed platform. Ahead, on the other side of the hangar, the belt on the far right disappeared into a tunnel.

Samantha looked down at the belt immediately to her right. It was moving faster than the one they were on. She couldn’t be sure how much faster. Then she looked at the far wall. They definitely had to reach the tunnel before they got to the end of the room.

“Grab my hand and wait until I tell you to go,” she said.

Samantha knew that, normally, Nipper was not the kind of boy who would want to hold any hands belonging to any of his sisters. But after their climbing, sliding, and tumbling around the world together, she figured he’d join her for a quick synchronized leap onto a moving walkway.

“One, two, three…go!” she shouted, and they hopped to the right.

Nipper let go quickly. He looked around. He frowned.

“See that?” he said, pointing at the surface of the belt.

There were yellow stripes every few feet, stenciled with black numbers and letters.

10 MPH

Samantha could tell Nipper was a little bit disappointed. He clearly thought it was going to be a more exciting ride. She nodded and pointed to her right. She didn’t try to hold his hand a second time.

“Ready, set…walk,” she said, more calmly this time, and stepped sideways onto the next belt.

Nipper followed and stepped beside her. They looked down again.

15 MPH

The end of the hangar was still far away.

“Ready, set, walk,” she said quickly, and they stepped again.

20 MPH

“Ready, set, walk.”

25 MPH

It didn’t feel like they were accelerating quickly. Each new conveyor belt added five miles per hour to their speed. She stopped directing Nipper as they continued walking from belt to belt.

30 MPH

35 MPH

40 MPH

45 MPH

Samantha felt a steady breeze through her hair as the slidewalk carried them along. It was a smooth ride.

They had almost reached the other end of the vast hangar. Ahead, nine of the ten conveyor belts ended at the wall. The tenth slidewalk, to the far right, disappeared into a tunnel. Samantha checked to make sure Nipper was beside her. Together, they stepped to their right, onto the last belt. A minute later, they coasted out of the hangar.

Samantha’s ears popped as she and Nipper entered the tunnel. The ceiling was just a few feet above their heads, and the brilliant light of the hangar panels had been replaced by rows of green and white lightbulbs that whizzed by. It was still easy to see, but everything had taken on a greenish tint.

Samantha glanced down, looking for stenciled speed stripes. She didn’t find any. Instead, she noticed that the surface of this belt was different from the others. It was completely covered with small plastic bumps. She figured they were meant to help riders’ feet grip the surface on the fastest belt.

“Okay, Sam,” Nipper called to her. “We’re on our way.”

She looked up. He pointed at a sign flashing the words TO MALI. She started to think about the letters A, L, I, and M again. She closed her eyes and tried to think. Were they going to the right place?

When she opened her eyes, Nipper had his arms out at his sides pretending to surf.

“Whee!” he shouted. “I’m going to do this all the way to Africa!”

Samantha began counting to herself. One, two, three…

Nipper put his arms down. He was bored, of course.

“So,” he said. “How fast do you think we’re going now?”

“Well, each belt sped us up five miles per hour,” she replied. “I think we’re moving at about fifty miles per hour.”

He nodded and started watching the white and green lights flash past them. After a minute, he turned back to her.

“How long do you think it will take to get to Mali?” he asked.

Samantha did some math in her head. It was 6,500 miles to Mali. Divided by 50, that was…130 hours. Divided by 24 hours in a day, that made…

Nipper, waiting, watched her.

“Five and a half days,” she said, and bit her lip, concerned.

Nipper stared. He looked around the tunnel and rubbed his chin thoughtfully.

“We really should have brought lunch,” he said. “And dinner…and breakfast…and lunch…and…”

It was going to be a very long ride.