Well, let them go. Rachelle and Marisol could spend the break squatting together under some bush. If Lavender couldn’t use the time to win Marisol back, she would at least prank the both of them.

Lavender slung another handful of pebbles and plopped down on the nearby boulder. Marisol was changing. Lately she was more interested in doing her hair than in classifying insects. Lavender didn’t even know if Marisol still wanted to be an entomologist. She talked more about starting a music channel on YouTube than about becoming a scientist. Lavender pulled the last of her trail mix out of her backpack and started chewing a handful of it with unnecessary force.

Sedgwick appeared out of nowhere.

“Brandon told Mrs. Henderson you were throwing rocks, and Mrs. Henderson told me to tell you not to throw rocks.”

“Mm-hmm,” Lavender answered. Her mouth was full of raisin, peanut, and melted chocolate, and she wasn’t in the mood to talk to anyone.

“Want to play hacky sack?”

“Not really.” Without looking at him, Lavender took another giant handful of trail mix.

Sedgwick didn’t take the hint.

“Do you know what a wash is?” he asked.

Lavender scrunched her face up at his random question.

“Mrs. Henderson keeps saying that Mr. Gonzales led us straight into a wash,” he explained. “I don’t know what that means.”

Lavender couldn’t resist explaining. She stuffed her empty bag of trail mix back in her backpack. “A wash is like a dry stream. When it rains, all the water runs off into washes and fills them up …” Her voice died out.

A terrible thought occurred to her. Washes were the most likely places to get caught in a flash flood. Every time a scary story came on the news about day-trippers or tourists getting caught or killed in a flood, Lavender’s mom would shake her head and talk about how dangerous hiking in Arizona could be.

“Sedgwick,” Lavender said slowly, thinking back to the warning she’d picked up on her radio. “Do you know what county we’re in?”

“Uh, this is A-mer-i-ca,” Sedgwick said.

“No. County, not country.”

Sedgwick shook his head, looking baffled. Lavender’s mind was racing faster than an electrical signal along a copper wire. On the off chance that there really was a flash flood, the class was in the worst possible place. Lavender grabbed her backpack and pulled it on. Before she could get away, Sedgwick pointed and asked, “Aren’t you going to use that strap?”

He always buckled the waist strap on his backpack.

“Sure, Sedgwick, whatever.” Lavender clipped the waist strap as she made a beeline for the closest teacher. Sudden anxiety was gnawing at her insides. Mr. Gonzales was playing hacky sack with a group of students.

“Mr. Gonzales!” she called out, startling him into dropping the ball.

An annoyed expression flitted over his face. “What’s up, Lavender?”

“What county is this?”

Instead of answering, he gave a very grown-up smirk. “Why the sudden passion for geography?”

“Just tell me.”

“Cochise.”

“Are you sure?” Lavender asked.

He nodded. “I might have gone off the trail a little, but give me some credit.”

Lavender’s heart rate shot up. “I think we need to get out of here.”

“Why?” Mr. Gonzales asked.

Lavender reached in her bag, found her radio, and flicked it back on. The National Weather Service was still repeating the same warning.

Mr. Gonzales listened, rocking back and forth nervously. “They extended it? When did they do that? It was supposed to end this morning.” As the announcement started over again, he suddenly broke up the game, waving his arms at the students and shouting, “All right, round everybody up. We’ve got to get out of here. We’re climbing those rocks. This way, everyone.”

“Shouldn’t we backtrack?” Lavender asked. “Isn’t that the safest way to find our trail without getting lost, like, for real?”

“That was a warning,” said Mr. Gonzales. “Not a watch like they had this morning. A warning means a flood either has already been spotted or is imminent. We have to take it seriously.”

“But it’s not even raining.”

“It could be raining miles and miles from here and a flash flood could come down a wash like this.” Mr. Gonzales glanced toward the distant clouds. “It’s just a precaution. But these things are unpredictable. You know what they say: Better safe than sorry. Come on, let’s get everyone moving. Now.”

A little spike of fear shot through Lavender. She wished that she’d known the difference between a watch and a warning sooner. She wished she’d asked sooner about the county. The class never should have ended up down here. Her hands shook as she jammed her radio into her backpack.

“Okay, listen up!” Mr. Gonzales raised his voice even louder than before. “I want everyone to get to higher ground. Let’s go. This way. We’re going to do a little rock climbing.”

“What in the world is going on?” Mrs. Henderson called from the other end of the wash.

“Flash flood warning came over the radio.”

“What radio?” Mrs. Henderson asked as she started walking in their direction. Then she gave her head a little shake before saying, “Never mind. Not important now.” As she neared Mr. Gonzales, Lavender heard Mrs. Henderson ask, “Do you really think we need to climb out of here?”

He nodded, and after a few more whispered words that Lavender couldn’t quite catch, Mrs. Henderson dragged Sarah toward the rocks at the side of the wash. Lavender tuned out the commotion around her—Sarah’s wails, her classmates’ questions, the parent volunteers’ orders—and concentrated on climbing up the steep slope until the sound of feet sliding over gravel and a short, sharp yelp grabbed her attention.

Lavender whirled around just as Kyle landed, smashing his knee into a rock. He must have slipped on the loose ground.

Amy and Jeffrey were closest to him. Jeffrey pulled Kyle up, and even from a distance, Lavender could see the blood running down his leg. Amy offered him a hand, and between the two others, he started limping after the rest of the class.

Lavender’s heart pounded as she scrabbled up the rock, watching her footing closely. No matter that Mrs. Henderson was repeatedly telling Sarah that flash floods were “incredibly rare” this time of year, Lavender wanted out of that wash, and she wanted out now.

Mr. Gonzales was shouting encouragement at the students; all the while, he kept pausing to count the class as he made his own way up the rocks. To calm her thundering heart, Lavender started trying to count her classmates, too. One, two, three … At eleven—Marisol’s favorite number—Lavender abruptly broke off. They were going to be two kids short when they finished counting.

Rachelle and Marisol were still hiding.

They didn’t know about the flood warning.

Lavender had lied, and they were in danger because of it. She had to go get them before anyone got hurt. Before anyone found out what she’d done.