Alex trawls through Lord Lucan’s belongings from his speedily abandoned flat.

She finds incriminating books where he’s torn out pages on how to kill your wife, and is taken aback by photos that make her reconsider the story.

She draws together what makes this a compelling crime, and asks what would give it the perfect ending.

And in a remarkable interview with a former Met Police Detective, she discovers that we could perhaps get an answer to one of the two mysteries tomorrow.

Presenter: Alex von Tunzelmann