It's not that the story about women who unwittingly helped develop the atomic bomb isn't fascinating. It is, right down to the shin-deep mud of their makeshift town in which many high heels were lost.

But it's difficult to read "The Girls of Atomic City" without wondering about a larger question: How in the world did the government ever pull off this secret operation?

The book explores how Oak Ridge, Tenn., was founded almost overnight, yet even with a peak population of 75,000 in 1945, never appeared on any map. Denise Kiernan started investigating this story in the nick of time, given that many of the people who worked on the Manhattan Project are aging; one source died before the book was finished.

She focuses on the young women who were tapped to work within the deep and soggy folds of the southern Appalachians as secretaries, custodians, statisticians and chemists. Some, such as Celia Szapka, were told only to get on a particular train and get off at a particular station. Others, such as Kattie Strickland, worked as a janitor when her husband found work at K-25 — the largest building under one roof at the time. She earned more than she'd ever known, but the trade-off was living alone because black couples could not live together there.

Kiernan's accounts ring with authenticity, which she supports with a detailed listing of interviews and source materials at the end of the book.

The town was built with such urgency that at one point, a house went up every 30 minutes. Young women lived in dorms, went to dances and played bridge. But always, there were the armed guards and the watchtowers. Some were asked to keep an eye on others, which made them wonder who was keeping an eye on them. Even the reason for Oak Ridge — to enrich uranium — was known only to a few, with the U-word never uttered. All most knew is that they were working with something called Tubealloy, for something related to the war effort.

The whole undertaking seems to have balanced on the head of a pin, with workers being told no more than the minimum to do their jobs. Everyone knew never to discuss work, even casually. Occasionally, someone would be escorted off the premises.

It was only with news of the bomb dropping on Hiroshima that most workers connected the disparate dots. The reality of what they'd done was both thrilling and appalling. Then … their work was done. As was the war.

Some moved away, but many remained in Oak Ridge. The town began appearing on maps. Schools were built, cemeteries established.

Kiernan's concentration on the women's role provides a necessary focus to her account, and as a historical glimpse, "The Girls of Atomic City" is fascinating. But Oak Ridge's most impressive legacy may be in the success of its secrecy.

And that leads to perhaps the largest question of all: Is such a project happening now?

Kim Ode is a features writer for the Star Tribune.