This Saturday marks the three-year anniversary of what’s often referred to as India’s 9/11 — the 2008 Mumbai terror attacks, a slaughter carried out by Pakistan-based terrorist group Lashkar-i-Taiba that left 166 dead, including six Americans.

Tomorrow, FRONTLINE and ProPublica tell the inside story of David Coleman Headley, the Pakistani-American who helped plan those attacks over the course of two years, and investigates the mysterious circumstances behind his relationship with the U.S. government.

Listen to ProPublica reporter and FRONTLINE correspondent Sebastian Rotella, who was on NPR’s Fresh Air today, as he describes how Headley, who grew up in Pakistan but moved to Philadelphia to live with his mother as a young man, moved from small-time drug smuggler to U.S. Drug Enforcement Agency informant to confessed terrorist.

Headley’s story is unlike any other, and, Rotella says, is “a gold mine for showing how this double game in Pakistan … is really played.”

A Perfect Terrorist airs tomorrow on PBS. We hope you’ll watch.