On August 4, 2020, a warehouse stacked with ammonium nitrate at the port of Beirut detonated, killing more than 200 people, wounding 600, and leaving 300,000 without homes. This episode of the engineering-investigation series What Went Wrong reconstructs the blast using footage of the shattered port, satellite and phone video of the mushroom cloud, and interviews with engineers and disaster analysts who walk through how roughly 2,750 tons of the chemical came to sit unsecured in a civilian harbor for years. The film traces the shock wave's path through the city, showing how it leveled the historic Gemmayzeh and Mar Mikhael districts and sank sixteen ships docked nearby. Analysts break down the chemistry of ammonium nitrate, the warning signs officials ignored, and the chain of bureaucratic failures that let the shipment languish unchecked. Rebuilt diagrams and blast-radius modeling sit alongside survivor and first-responder accounts, giving the disaster both a technical explanation and a human scale. The result is a compact account of how negligence turned a stockpile of fertilizer into one of the largest non-nuclear explosions on record.