Richard Esposito and Jim Sciutto (ABC News)
The London bomb plot failed because a medical syringe used as part of the firing mechanism caused a malfunction, despite multiple calls to the cell phones designed to remotely trigger the devices. Had the fuel-air bombs rigged inside the Mercedes parked near the front door of a nightclub successfully ignited into a superhot fireball filled with roofing nails, enormous casualties were almost a certainty.