Shannan Gilbert was last seen pounding on doors in a gated community on Long Island before sunrise on May 1, 2010. At least two Oak Beach residents called 911. But by the time police arrived, she had vanished.

Six months later, the search for Gilbert turned up the identically wrapped skeletons of four other women along a nearby highway. Like Gilbert, all had been in their 20s and working as escorts, advertising online. Some were mothers, some had been good students. From struggling hometowns in Connecticut, Maine, outstate New York and North Carolina, they disappeared from 2007 to 2010.

Robert Kolker, an investigative reporter covering the eerie case for New York magazine, invited the mothers and sisters of the five women to breakfast in Manhattan a year after Gilbert disappeared. All came, hoping to keep pressure on the investigation. Six months after the interview ran, Gilbert's body was found near the same highway. But no arrests.

In "Lost Girls: An Unsolved American Mystery," Kolker hands his considerable findings over to us. Here is access to a world a lot of us would rather not think about and a way to confront the larger mystery of why women's deaths in the sex trade are still considered inevitable.

It is a fast and compelling read, well organized and researched, illustrated with ghost maps in gray and black that evoke the night landscape. Gilbert's story drives the narrative, the first half devoted to the women's stories, the second half to an investigation riddled with gaps and delays.

Kolker writes masterfully about place, from fast-food alleys of industrial towns to the poison ivy-infested salt marsh of Oak Beach. His human portraits are sharp yet compassionate, rendered in rough language and complicated by subplots of addiction and economic hardship.

Robert Kolker

The women in "Lost Girls" post their own ads and pay a driver instead of working for a pimp. Through tough times, there is big money to be made underground by enterprising women using the latest technology. One Oak Beach victim had "made enough to come home to Buffalo at Christmastime and take [her sister and mother] to a spa for massages. 'You deserve to be pampered,' she said. On Christmas morning, [her sister] and all the cousins each unwrapped an iPod Touch."

The stories of the women and their families did not let Kolker go. One sister, describing the ache of a chance encounter with her orphaned nephew, said she came away "thinking that God puts you in places for a reason." "Lost Girls" is Kolker's worthy work to make that true for the victims at Oak Beach.

Gayla Marty is the author of "Memory of Trees: A Daughter's Story of a Family Farm," now in paperback. She lives in Minneapolis.