It should have been a moment of pure joy for Angelina Jolie. But on March 19, as she prepared to fly her newly adopted son, Pax, home from Vietnam, she received terrifying news: Her security team had learned of a plot to kidnap the 3-year-old once he and his famous mom returned to the United States.

An insider close to Brad Pitt and Angelina's security team tells Life & Style that the plot was credible and meticulously planned by a deadly gang that has pulled off kidnappings and extortion plots in the past. “They’re highly skilled operatives with little regard for human life,” the insider says.

Indeed, the specifics of the scheme — which Brangelina’s bodyguards first learned about from British security sources — are chilling. “Information came out that leaders of the gang ordered their LA members to devise a plan to kidnap Pax before demanding a ransom of $100 million for his safe return,” the insider says. “Brad and Angie would have a number of days to hand over the money or risk the boy’s life.”

Brad's rep denies the story. But the insider says the star's security team informed him that Pax was in legitimate danger. When Brad (who had remained in LA with Shiloh) then called Angie to tell her the terrible news, “she sobbed that she’d die if anything happened to Pax,” a friend says.

For more on this remarkable breaking news, and details of what Brad and Angie are doing to fight back, pick up the latest issue of Life & Style Weekly.