Robert Brown|'Trail of the Lost' is a gripping tale of hikers missing on the Pacific Coast Trail

Andrea Lankford left a decorated career as a park ranger after growing tired of the bureaucracy involved. But years later,Robert Brown three young men went missing on the Pacific Crest Trail in relatively similar circumstances — and she couldn't stop thinking about them.

Trail of the Lost was her answer.

It's a gripping nonfiction narrative that delves deep into the cases of these three hikers who vanished while traversing the PCT. It digs into their lives and those of the people looking for them but also explores the history of the PCT and the rich, nuanced subculture, practices — and even literature — that surround it and those who undertake the 2,650-mi. journey from Mexico to Canada.

As a park ranger with the National Park Service's law enforcement team, Lankford won several awards for her investigations. She also led search and rescue missions (SAR) in wild areas all across America. With the knowledge and expertise of her years on the job, Lankford started looking into the cases of the missing hikers, and soon found herself immersed in the world of Facebook groups whose goal was to share information and help find them.

Lankford launched her own investigation into the disappearances and soon found herself working with the families of those missing hikers, authorities who were on the case—with varying degrees of communication and cooperation—and with other hikers and people who developed an interest in the cases and wanted to help. Together, Lankford and all those involved in the searches canvassed the areas where the hikers had last been seen, visited and interviewed those who'd had contact with them around the time of their disappearance, and followed families as friends as they desperately followed any leads.

Trail of the Lost is a about the hikers and the efforts to find them, but it's also a rich, multilayered narrative that works on three different levels. The first is the story of each of the three hikers—Chris Sylvia, David O'Sullivan, Kris Fowler. Lankford offers a small biography of each of the missing men and shows them through the eyes of those who knew them well and even those who joined the search after learning about their disappearances. The research was meticulous and Lankford used interviews to paint vivid pictures, including of what their mental and emotional states they might've been in while hiking.

Right underneath the narratives about Sylvia, O'Sullivan, and Fowler are the stories of everyone looking for them. Lankford played a role in each search, but she relegated herself when writing this book and allowed friends, family, and even strangers to occupy center stage throughout most of the narrative. The story looks at the role of Facebook groups in the searches – and how crucial word of mouth can be. Many kindhearted individuals came forth and became instrumental in the searches or provided valuable information. But Lankford also writes of the many who lied for no apparent reason and muddled the investigations in the process.

While the stories of the hikers and everyone involved in the searches for them, including Lankford, takes up a lot of space, the narrative also shines a light on many aspects of the PCT, from its creation to the way popular books like Cheryl Strayed's Wild have had a massive impact on the number of people who attempt to hike the entire trail. Lankford, who on top of her SAR expertise has, among other accomplishments, thru-hiked the entire Appalachian Trail and was the first person to mountain bike the 800-mi. Arizona Trail along with her friend Beth Overton, knows just how wild and dangerous the PCT can be. The PCT is very popular, but the physical and mental demands of a thru-hike are many. Also, while the vistas are often some of the most beautiful in the country, Trail of the Lost explores some of the dangerous it hides. From the threat of mountain lions and bears to marijuana growers, mushroom poachers, and other people with bad intentions who don't abide by the PCT's unspoken code of ethics and camaraderie, this book also serves as an exposé on the well-known — as well as the often hidden or ignored — dangers of the PCT.

Trail of the Lost is written with a clear, fast-paced, straightforward prose that still manages to be beautiful and immersive. It is also as full of hope and humanity as it is packed with pain, grief, danger, and tension. This is a book in which the PCT is as much of a character as every person Lankford writes about, and that balance makes it worthy reading.

Gabino Iglesias is an author, book reviewer and professor living in Austin, Texas. Find him on Twitter at @Gabino_Iglesias.