Fictional story of a flash mob gone terribly wrong

Tom Scott's Ignite London talk "Flash Mob Gone Wrong" is a fictionalized account of just how badly a flash mob could go. It's got an eerie ring of plausibility, largely because each of the steps leading up to the disastrous ending actually happened, just not all together. It's a freaky way to spend five minutes.

Flash Mob Gone Wrong by Tom Scott, Ep 77