Fifty years ago, Lord Lucan murdered Sandra Rivett then disappeared. This surreal series follows the victim’s son as he hunts down the fugitive peer – and ends up somewhere totally unexpected

Richard John Bingham, the 7th Earl of Lucan, was declared dead in 1999, but that did nothing to halt the highly profitable cottage industry of speculation about him, which has chugged away since 1974, when he murdered Sandra Rivett, his children’s nanny, then disappeared.

At first glance, you might think that this three-part documentary will be another contribution to this conspiracy-minded canon. But this is not a “have we found him?” film. I cannot emphasise enough how much it is worth sticking with it until the end. What unspools is a sometimes tender, sometimes troubling rollercoaster that ends up in surreal and unexpected territory. There is a fake monk, catfishing, drag queens and Timothy Leary. You have probably not seen this side of the Lord Lucan story before.