The kid scientists are in Yellowstone National Park, checking on a wolf pack they last saw one year ago. Kai is a zoologist. He and his team study animals and how they behave in their environments. Their latest assignment: observing wolves in Yellowstone National Park. Using a combination of old and new technology, Kai's team checks the pack's health and its effect on the environment. Inspired by a real-world study, this story introduces readers to the terms, tools, and techniques zoologists use in their research, including bioacoustics, the study of making and receiving animal sounds.