"But he doesn't have any proof, so he called you, since you happen to be not only the love of his life but also an incredible detective,"

"Thanks for the compliment, but I'm really worried about this case. This phase of the Emerson study ends on Saturday. Ned says that if any marmots vanish between now and then, the study could be blamed. The third phase of the project scheduled for this summer would be canceled, and all the college's work would go down the drain." Nancy sighed. "Ned's really upset."

"You don't think that someone from the Emerson group could be involved, do you?"

"I'd hate to think it. But we've got to check," Nancy said solemnly as they passed a sign that said South Entrance, Yellowstone National Park.

Tall, slender lodge pole pines lined the road on either side, their tangy scent filling the car. The trees were so thick in some places that it was like driving through a tunnel.

"I can't wait to see the yellow-bellied marmots," Bess said.

Nancy grinned. "Ned said they look like chubby, overgrown chipmunks, only with yellow undersides, which is how they got their name. But most people call them whistling marmots, because they communicate by making high-pitched sounds."

"They sound cute-" Bess began but stopped abruptly.

A herd of brown elk appeared from among the trees on the right.

Nancy stepped on the brake.

Paying no attention to the car, the elk began prancing gracefully across the road.

"Oh, Nancy, look at the babies!" Bess cried. Nancy chuckled as a handful of little elk wobbled awkwardly in front of the herd.

The herd stopped in a meadow on the left side of the highway. Near the center of the sparse grass where the creatures were grazing, Nancy noticed a cone of gray rock about a foot high. From its center, wisps of white steam curled into the air.

"It's a geyser!" Nancy exclaimed.