Detail by painful detail, the CIA is coming to grips with one of the most devastating episodes in its history, a botched cloak-and-dagger flight into China that stole two decades of freedom from a pair of fresh-faced American operatives and cost the lives of their two pilots.

In opening up about the 1952 debacle, the CIA is finding ways to use it as a teaching tool. Mistakes of the past can serve as cautionary tales for today's spies and paramilitary officers taking on al-Qaida and other terrorist targets.

Bits and pieces of the story surfaced over the years. But the lid was largely intact until a series of disclosures — some required of the CIA, some not — revealed a tale of tragedy, miscalculation, misery and personal triumph, as well as the agency's misplaced confidence it could manipulate events in China....