Is courage a little bit mad? When a man with a knife attacked Australian shoppers on Saturday, a policewoman ended the nightmare. What motivated her is a matter of debate.
Heroic officer who stopped the Sydney killer
Facing danger: Inspector Amy Scott (above) was alone when she shot the knifeman. Glossary
Achilles - The Greeks' greatest hero. The only vulnerable part of his body was his heel - hence the expression "an Achilles heel", meaning a weak spot.
Hormone - Chemicals carried in the bloodstream that alter the way your body's systems act.
River Hudson - A river that flows through New York.