As a schoolgirl in North Korea, Hyeonseo Lee was forced to watch executions, denounce her friends for fabricated transgressions and dig tunnels in case of a nuclear attack.

But Lee and her classmates grew up convinced they lived in the "greatest nation on Earth," run by a benevolent god-like leader whom they loved in the way many children love Santa Claus.

It wasn't until she left North Korea at the age of 17 that she began to discover the full horror of the government that had fed her propaganda since birth.