What do you get when you combine a wildlife researcher's knowledge with a gripping plot and an admirable and likable protagonist? You get the books in Alice Henderson’s highly acclaimed series, the third installment of which is A GHOST OF CARIBOU.

In each title, Henderson cleverly uses the group noun for the animal that Alex Carter is researching. She wrote about “a solitude of wolverines” and “a blizzard of polar bears” in the first two entries, and now the focus shifts to caribou. In addition to the fine writing and the characters I have come to care about, I love learning about the wildlife. Caribou? I had no idea that we had them in the US until I read this thrilling novel.

As a wildlife researcher for the Land Trust for Wildlife Conservation, Alex is responsible for investigating different species. This time, she is studying whether or not there is a caribou in Washington State; one might have been spotted on a remote camera. We are given a lot of info about caribou and how they differ from similar species like deer and elk.

"Have I enjoyed this series? Absolutely. Do I relish the action and the mystery, and learning about the environment with details I wouldn't otherwise encounter? Indubitably."

Henderson never lectures, and the lessons, so to speak, are delivered naturally as part of the process of Alex’s work. But we come to care about the animals, and it's extremely frustrating to see the futility of our Federal Endangered Species Act and its decades-long inability to protect species that are endangered but have not been formally listed. The bureaucratic process works so slowly and inefficiently that there is a real possibility that species will go extinct before anything significant is done.

Henderson writes, "The Endangered Species Act was a valuable piece of legislation, but Alex had come to believe that its approach might be outdated. It dealt with species as if they were isolated problems to solve. In reality, things needed to be addressed in a more holistic way. What we need is an Endangered Ecosystem Act, she thought. Protection that addressed an entire ecosystem would benefit so many species at once: wolverines, mountain caribou, the American pika, and, of course, even human." This especially resonates with people like me who have been watching the indiscriminate slaughter of wolves in Montana this hunting season.

Henderson is passionate about our environment, and she emphasizes the damage that climate change is causing not just in terms of more destructive and uncontainable wildfires, hurricanes and warmer temperatures, but to the wildlife itself. She points out that we are "currently experiencing an insect apocalypse that was going largely unreported. Insects had declined by 75 percent in the last fifty years, due to loss of habitat, pesticide use, and climate change." Then she explains why this devastation is so frightening.

The mystery is well done. When Alex arrives at the land that the Trust has purchased, a dead body is found in town. She is asked to keep an eye out for a hiker who went missing the previous year as mysterious lights fly through the forest at night. One local is convinced that aliens are responsible, but knowing that Henderson is a scientist, we don’t think that's where the story is headed. But there are times when we want to scream at Alex for taking unnecessary chances. She knows there is danger in the area yet stays out overnight. She also doesn't tell the local sheriff about the lights at first, and we're not sure why.

The writing is engaging as Henderson describes the sights and aromas in the wild: "Here, towering western red cedar and western hemlock trees grew to immense proportions, lichen hanging off their branches. The soil smelled damp and earthy, and she lingered, reveling in being out here in the mountains, the crisp air on her face."

Have I enjoyed this series? Absolutely. Do I relish the action and the mystery, and learning about the environment with details I wouldn't otherwise encounter? Indubitably. Do I think that newcomers should read each book chronologically? Yes. That way, they truly will get to know Alex Carter's background and what she does, which will only add to their appreciation of the series.