Tony Robinson and science journalist Becky McCall step into the unknown to investigate whether past paranormal events should be taken seriously.

During the Second World War Helen Duncan proved to be an uncannily accurate medium, and the last person to be jailed under the Witchcraft Act of 1735. Her claims were taken so seriously that MI5 became involved. But was she really a threat to national security, and were the ghosts of wartime servicemen telling her secrets she should?