Terrorist Snake Oil

Red mercury — precious and rare, exceptionally dangerous and exorbitantly expensive, its properties unmatched by any compound known to science — was the stuff of doomsday daydreams. According to well-traveled tales of its potency, when detonated in combination with conventional high explosives, red mercury could create the city-flattening blast of a nuclear bomb. In another application, a famous nuclear scientist once suggested it could be used as a component in a neutron bomb small enough to fit in a sandwich-size paper bag.

Except it doesn't exist. Red mercury is akin to the mythical Glock 7 that couldn't be detected by airport x-ray machines.