“The British cell was planning to smuggle those liquid bombs onto planes and blow up seven airliners heading to North America, with at least 1,500 people onboard. That would have made it the biggest loss of life since 9/11,” Mark Kelton, former CIA chief of European operations, tells The Daily Beast. “And if the bombs had gone off over a populated area, the casualties would have gone up exponentially.”

Kelton, a 34-year veteran of the CIA, was one of the central figures who helped thwart this plot. An ex-CIA senior executive, Kelton not only served as chief of European operations for the CIA but also the CIA’s counterintelligence chief. Additionally, he served as chief of CIA ground operations in Croatia, Austria, Russia and Pakistan, and as the station chief in Pakistan helped coordinate the raid that killed Osama bin Laden.

“What led us to bin Laden was the work of hundreds of people over a decade from all intelligence agencies, working together as a team,” Kelton says.

And it’s in Pakistan that the story of the Transatlantic Liquid Bomb Plot begins.