Ever wonder how the American Volunteer Group got its nickname "The Flying Tigers" when the noses of their P-40 Tomahawk fighters were decorated to look like sharks?

It took more than 50 years for the Pentagon to fess up to the truth about the 100 American pilots and mechanics who formed the storied fighting group that helped China shoot Japanese bombers out of the skies over Kunming in the months before Pearl Harbor.

Namely, that it was a covert operation, approved at the highest levels of the White House by executive order, in flagrant violation of America's policy of neutrality and hidden from an adamantly isolationist Congress.

And for 75 years, the most detailed accounts of the Flying Tigers' exploits — pilots' diaries and letters, combat reports and other official documents — lay growing mold in the basement of a brick building in Georgetown.

Now author Sam Kleiner has done the admirable service of digging through those records and not only bringing the story to life, but doing it in a way that reads like a thriller.

The Flying Tigers: The Untold Story of the American Pilots Who Waged a Secret War Against Japan (Viking) is an eye-opening account of intrigue, espionage and heroism.

The story begins, as it should, with Claire Chennault, who founded the group, growing up in the backwoods of Louisiana the son of a cotton farmer, learning how to shoot and trap and live off the land. His favorite book was Huckleberry Finn and he wanted to be a teacher.

Until he went to the State Fair in Shreveport in November 1910 and saw a demonstration of an early biplane. That changed everything.

Determined to fly, Chennault missed the opportunity to train in the Great War but persisted and eventually became an ace for the Army, heading a trio of aerialist performers called the Three Men on the Flying Trapeze.

When they performed at the Miami Air Races of 1935 — the largest gathering of airplanes ever at the time — there were a few people of significance in the audience: the British and Nazi air force attaches from Washington and a delegation of Chinese military officers shopping for new planes and squired by American businessman and adventurer William Pawley (described by his biographer as "a cross between Indiana Jones and Donald Trump").

Pawley had been making a fortune selling Curtiss-Wright planes to the Chinese and had just opened an assembly factory in Hangchow (now Hangzhou). He asked Chennault's trio to join him on his yacht. There they were invited to China to help train its fledgling air force.

And the rest, as they say, is history. Chennault explained his decision to accept the Chinese offer in a letter to his brother. His work there "may amount to very little except a good paying position or it may amount to a great deal." But destiny was calling him. "It is even possible that my 'feeble' efforts may influence history for some few hundreds of years."

The air fights in the book are right out of Hollywood, only more immediate with all of the wonderful first-hand accounts in the pilots' own words.

As for the origin of the shark nose designs on the P-40s, the pilots were drinking gin one evening in the Burma jungle in 1941 when one of them picked up a copy of Illustrated Weekly of India. It had a photo of an Australian P-40 on the cover, with the shark jaw design. Chennault not only liked it, he had the design painted on the whole fleet.

The tigers nickname came in a Dec 29, 1941, Time magazine article titled "Blood for the Tigers", describing how "the Flying Tigers swooped, let the Japanese have it" in the skies over Kunming.

"Chennault later claimed he had no knowledge of the origin of the name 'Flying Tigers' and was 'astonished' to see it in the press," Kleiner writes.

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