One winter's night, 50 years ago, a crime took place that obsessed the nation.

Lord Lucan is said to have killed the family nanny, attacked his wife and vanished. Why did this case capture the British imagination, and spark one of the greatest unsolved mysteries of the 20th Century?

Alex von Tunzelmann unpacks the story of our obsession, taking us into a dizzying world of high stakes gambling and exclusive London clubs, powerboat racing and pet tigers. It's also a dark realm of bankruptcy, gaslighting and stalking, and at its heart, a story with a violent and very tragic death.

She tries to get to the bottom of this case, meeting eyewitnesses from the '70s, people caught up in the crime, and those who just can't let it go. Told and retold, the facts of the Lucan story have got lost. Alex discovers a hall of mirrors where truth and lies have distorted themselves into new myths and new mysteries.

Was the truth obscured by booze and backhanders, class deference and journalist spin? As the stories and conspiracies swirl around her, Alex herself gets caught up in the Lucan obsession. Across the series she unearths long forgotten tapes and letters, piecing together the fragments of the legend to discover why the Lucan myth still holds such power.