After the introduction of a new computer system in the early 2000s, the Post Office began using its data to accuse sub-postmasters of falsifying accounts and stealing money. Many were fired and financially ruined; others were prosecuted and even put behind bars.

In this ten-part series, journalist Nick Wallis, gets right to the heart of the story, as he talks to those whose lives were shattered and follows the twists and turns of a David and Goliath battle as the sub-postmasters tried to fight back.

Today, the sub-postmasters have hit rock bottom. Working with the Post Office has failed and their last hope is a long shot lawsuit. But Nick manages to get hold of some crucial documents and a whistleblower which might make all the difference.

Presenter: Nick Wallis