Mercedes shook her head. “I told you,” she said impatiently. “I don’t know a thing. The contest was already set up when I first heard about the trip.”

“Well, then, maybe you can tell me something about Paula’s business,” Nancy went on, “or about her friendship with Max.”

Mercedes frowned. “I don’t think they were friends at all. Max was just somebody who was available for this trip. Somebody who knew the river.”

“Okay, what about her family?” Nancy asked. “Did your families see each other very often?”

Mercedes looked away. “Why do you want to know? There’s no point in dragging up the past.”

“What past?” Nancy asked sharply.

Mercedes looked flustered. “I-I just meant the things that have happened in the past two days,” she said. “We’ve got to get out of here. What’s the point in trying to figure out why things happened the way they did? Especially now that-” She choked. “Now that Paula is dead.” Her eyes filled with tears and she turned back to the fire.

“You might be right. But why,” Nancy persisted, “weren’t you surprised to learn that Paula had taken the compass? Why did you suspect her?” Nancy knew that if Mercedes would open up, she’d have the key to the case.

“I don’t want to talk anymore,” Mercedes said sullenly. “You can’t make me talk to you.”

“No,” Nancy admitted. “But when we get back to civilization, the police can.”

“I’ll cross that bridge when I come to it,” Mercedes said, removing the pot from the fire and standing up. “Who knows? We might not even get back to civilization. We’ve still got another day to go, at least.” She turned away from Nancy. “Okay, everybody,” she called, “the soup’s ready.”

While Nancy was eating the soup and the piece of beef jerky she had been rationed, she thought about what Mercedes had told her: There’s no point in dragging up the past. Nancy was sure Mercedes hadn’t meant the events of the last two days. In fact, she was sure Mercedes knew something-something she wasn’t telling. Something she wouldn’t tell.

Nancy snuggled into Ned’s jacket, glad he wasn’t cold and she could keep it around her. Then she frowned, thinking more about the case. Sure, there weren’t a lot of clues, but she sensed there were a couple of possibilities right under her nose that she was overlooking. Every once in a while they began to form in her mind, then vanished before she had a chance to focus on them.

Well, she thought resolutely, Mercedes couldn’t keep her from finding out the truth. Nothing could, not even the frustration she was feeling. Nancy Drew always got to the bottom of things, and she’d get to the bottom of this case, too-if it killed her.

When supper was over, everyone huddled wearily around the fire, scratched and sore from their long hike. There wasn’t much conversation. It was a moonless night, and outside the circle of firelight, the dark pressed in ominously.

Then in the near distance, the quiet was shattered by an eerie scream.

“What was that?” Linda cried out, clinging to Ralph.

Tod laughed. “Just a mountain lion,” he replied.

“But don’t worry,” Mike said. “A mountain lion won’t attack you unless you corner him. He’s a whole lot more fond of rabbits and ground squirrels than he is of people.”

Sammy shivered. “Well, he can keep his rabbits and his ground squirrels,” she said. “I’ll settle for a hamburger with fries and onions.”

George groaned tragically, rubbing her stomach. “Please. Don’t talk about real food. You might just as well knock me out-it would be much kinder.”

Nancy threw a glance at Ned, who was sitting next to her. Now was the time to tell everyone what had happened before supper that evening. Briefly, she told her story.

“It must have been Max!” Ralph and Linda exclaimed when Nancy had finished.

“Max?” Bess asked, in a half-longing voice.

“Oh, will you stop, Bess,” George said impatiently. “Haven’t we got enough trouble without-”

“It’s trouble, all right,” Nancy said. “If Max really is dangerous, he’s not going to let us out of here to tell the police what happened.”

Bess shook her head stubbornly. “I can’t believe that.”

“You might believe it if you’d been standing on that trail, staring up at that boulder coming down on Nancy,” Ned said. “It was as big as a house. And it sounded like a freight train.”

Nancy shuddered, remembering how frightened she had been-and how strong and supportive Ned’s arms had felt around her when for a minute she had lost her own strength. It was ironic, she thought. She had wanted Ned to come on this trip so that he could feel a little protective about her. Well, he certainly was protecting her.

“Yeah, but you don’t know that somebody pushed the rock,” Bess was insisting. “It might just have come loose. After all, rock slides happen here all the time, even when there’s no one around. Anyway,” she went on insistently, “you aren’t even sure you saw somebody up there. How do you know that it wasn’t just your imagination?”

“I don’t,” Nancy admitted. “Just the same, we can’t afford to take any chances. If Max did push that boulder down, he’s dangerous.” She looked around at the group. “We’ve got to be careful.”

“Careful?” Sammy asked, frowning. “And just how do we do that?”

“Well, for one thing,” Nancy answered, “we shouldn’t go off by ourselves.”

“Yeah,” Ned said, “and we need to pay attention to what’s going on around us, so that Max isn’t able to sneak up on us.”

“Then it might be a good idea to keep watches tonight,” Mike said, stirring the fire.

“Right,” Nancy agreed.

“I was afraid of losing sleep tonight,” Bess said, making a face, “but I had it figured a little differently. I thought my hunger would keep me awake!”

Ned drew the first watch and Nancy the second. “I’ll wake you up in an hour,” he promised as Nancy crawled under her blanket between Bess and George. He bent over and kissed her.

“Thanks,” Nancy said sleepily. “And Ned?”

“Uh-huh?”

“Thanks for being there this afternoon. It feels good to be alive.” She smiled. “You know, if we get out of this in one piece, I swear I’ll never take another vacation the rest of my life. Detective work is a lot safer!”

Ned laughed and gave her another quick kiss.

In an hour, he awakened her and she took her turn beside the fire. At the end of her hour, she woke Mike, who had the third watch, before going back to sleep. But her dreams were full of gigantic boulders that roared down on her.

Nancy woke at dawn, curled up into a tight ball, cold and stiff. The campfire was out and Ralph, who had the last watch, was drowsing beside it.

No wonder I’m cold, Nancy thought. My blanket slipped down. She tugged on the blanket, but the end of it seemed to be caught on something. A rock? She raised her head to look-and froze.

A huge rattlesnake lay coiled on the blanket. At Nancy’s movement, its head came up, staring at Nancy with beady amber eyes.