BBC iPlayer series you need to watch asks more questions than it answers
Neil Berriman is a man with a mission. Neil, a builder from Hampshire, wants to track down Lord Lucan - or at least find out what happened to the missing peer.
In this, Neil is not alone. The fate of Lucan, missing ever since his children's nanny was found murdered at his Belgravia family home, has been a preoccupation for journalists, detectives and armchair investigators for 50 years.
But for Neil, it's different. After the death of his adoptive mother, he discovered he had a personal link to perhaps the most notorious missing person in UK history.
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Neil's biological mum, Sandra Rivett, was the nanny found dead at the bottom of the basement stairs on November 7, 1974. This fact has dominated his life for 17 years, during which he has worked to trace what happened to Lucan, who was declared officially dead in 1999.
And while the BBC's three-part series Lucan bears the name of the professional gambler known ironically to his friends as Lucky, it's really about Neil. In fact, it's really about obsession, and where a determined refusal to let something drop can take you.
Director Colette Camden follows Neil and former BBC journalist Glen Campbell as they pursue leads, ultimately settling on the conviction Lucan, who would now be in his late 80s, is living out his days in Australia via a life of Buddhist retreats and serial name changes.
Initially, Glen's natural ebullience, contacts and professional skills seem to be the driving force behind the quest, while mild-mannered Neil simply wants answers about his mum and the man suspected of her murder. But throughout the documentary it becomes clear that while Glen wants to find Lucan, Neil needs to - regardless of the cost to himself and his relationships.
This three-part documentary treads a narrow, delicate path as it traces Neil's pursuit of leads, weaving in the history of Lucan, whose moral world seemed to stretch no further than the casino doors.
Camden never judges Neil and his utter conviction that his mum's likely killer is not only alive and well but has evaded capture until now. His belief is a testament to the strength of a son's love, of tenacity in the face of adversity and of a bulletproof degree of certainty - at all times, without question.
Whether this is a good thing, or healthy, is something viewers are left to judge. I won't spoil anything, but throughout the three episodes viewers are likely to swing between dismissive scepticism and a sneaking feeling that maybe, just maybe, Neil is on to something - and then back again.
Whether you're a Lucan aficionado or new to the mystery, Lucan is well worth catching up with. Like the case at its heart, it may offer up more questions than answers - but sometimes questions are all we've got.