Knowledge can be dangerous. As neuroscience delves more deeply into our organ of thought and its complex soup of neurotransmitters - could it also be exploited for malign purposes? Is the brain the next target of terrorism? Pharmaceutically enhanced soldiers, chemical torture, incapacitants, neurological weaponry... The possibilities are frightening and progress rapid. Two leading researchers into biological weapons present their concerns, and argue scientists need to take action now. But are we at risk of paranoia?