Million Dollar Lover is an unlikely love story, recorded in real time as the relationship unfolds between Carolyn, who is 80 and has properties worth a few million dollars, and Dave, 57, a former drug addict who is homeless and has spent a decade in jail.

The story captured the attention of the BBC Journalist Sue Mitchell, as it was unfolding on her street. She spends a lot of time in California – she married an American and her award-winning journalism has been about the lives of people like Dave who inhabit the dangerous margins of society.

There are so many homeless people in America that the wealthy can no longer avoid contact with them. When Dave arrives in Cayucos, a charming beach town, prosperous and sunny all year round, he goes to church. Some people there try to help him find work and recommend him to Carolyn as an odd job man. She falls in love with him and within a fortnight, Dave has moved in.

Dave is a talented man – a skilled joiner and musician who makes and sells jewellery. With Carolyn’s support, he is ambitions for his future. He appears to be thriving and so does she. But she is vulnerable following the death of her husband. Her family fear she is showing signs of cognitive decline and she certainly struggles to manage her finances. She also yearns to feel the love that comes from a romantic relationship and to feel needed again.

Her neighbour, Marie, says it is something she sees a lot amongst the elderly people she cares for; it is a desire to be loved and to be in love which does not diminish with age. Marie cautions Carolyn against rushing into a relationship with Dave, but it is too late. Soon Marie is left watching from the side-lines as Carolyn starts cutting off friends and relatives who question her.

Her middle-aged daughters are increasingly worried for their Mum and for the money they expected to inherit from her; a property portfolio which their parents and grandparents had built up over the years. They fear Dave might be taking advantage of Carolyn and ask her to be assessed for mental incapacity: it seems the only explanation they can find for why she has fallen so deeply under his spell.

Sue Michell is a skilled investigator who uncovers horrors in Dave’s past that he has never mentioned to a living soul. She also brings her knowledge of elder abuse and exposes how the process of ageing makes subtle changes that can alter how we see others - particularly strangers who seem loving, young, and strong.

Is Dave really a tender carer who will cherish Carolyn to the end as he promises, or is he a dangerous interloper who will fleece Carolyn – breaking her heart and her family?

New episodes will be released on Thursday, wherever you get your podcasts. But if you’re in the UK, listen to the latest full series of Intrigue first on BBC Sounds. https://bbc.in/3WEQS5W

Million Dollar Lover is produced by BBC Audio, the team behind The Boy in the Woods and is presented by Sue Mitchell.

The series is scripted by Winifred Robinson; the producers are Sue Mitchell and Joel Moors; the dramaturg is Flo Dessau and sound design is by Tom Brignall. The series Editor is Philip Sellars

The idea of living forever has captivated us for millennia, but rarely do people imagine what would happen the day after the fountain of youth is discovered. Today’s technology entrepreneurs pushing an immortality agenda - through their investments and their influence - seem only focussed on the pursuit.

Whether or not immortality is a distant possibility, how do we cope with living longer en route to forever? Where’s the planning for that? It’s a great opportunity for innovative thinkers but, from what we’ve seen over the last two decades of technological disruption, these real but smaller goals aren’t nearly as enticing as the big ones.

In this series, technology reporter and psychologist Aleks Krotoski explores the frontiers of the extreme longevity pioneers. They've made their money in Silicon Valley. And with their technology solutions - PayPal, Facebook, cryptocurrencies - they've ushered in the world that we live in today, with all its unintended consequences. Some of them now want to solve the "problem" of aging, or even death, and they are making bigger strides than we may think.

Can they? Should they?

A Pillowfort production for BBC Radio 4

New episodes released Mondays. If you're in the UK, listen to the full series of Intrigue: The Immortals first on BBC Sounds: bbc.in/3WEQS5W

The immortalist movement in Silicon Valley shares a lot with evangelical religions, says Dr Emile P Torres, a philosopher and former Nick Bostrom acolyte. In both, he explains, there’s a heaven in which the faithful will experience unsurpassed bliss and delight, and an apocalypse, which will separate out the people who can go there.

After a decade at the epicentre of the transhumanist research community, Emile became concerned with the number of apocalyptic stories of techno-utopia that were being shared online. Was this philosophical movement becoming radicalised? When Emile raises the question, the consequences are swift and severe. Excommunicated, harassed and threatened.

With influential and powerful technology billionaires as some of its faithful, is Emile right? Is this movement really one of the most dangerous secular ideologies?

In this series, technology reporter and psychologist Aleks Krotoski explores the frontiers of the extreme longevity pioneers. They've made their money in Silicon Valley. And with their technology solutions - PayPal, Facebook, cryptocurrencies - they've ushered in the world that we live in today, with all its unintended consequences. Some of them now want to solve the "problem" of aging, or even death, and they are making bigger strides than we may think.

Can they? Should they?

A Pillowfort production for BBC Radio 4

New episodes released Mondays. If you're in the UK, listen to the full series of Intrigue: The Immortals first on BBC Sounds: bbc.in/3WEQS5W

A new philosphical movement is gathering steam in Silicon Valley, one that promises immortality by using technology to solve the problem of death. This movement is led by Oxford philosopher Nick Bostrom.

Professor Bostrom is the author of Fable of the Dragon Tyrant, the original manuscript of the modern immortality movement. It was published in 2005 in the Journal of Medical Ethics as a response to what Bostrom described as the absurdity of the inevitability of accepting ageing and death. Far from being a one-off, the Fable is one of the core texts that form part of a moral philosophy of the future of humanity called transhumanism. Adherents believe that we will achieve immortality by merging with artificial intelligence and becoming “post-human", and that the next step in our human evolution is nigh.

In this series, technology reporter and psychologist Aleks Krotoski explores the frontiers of the extreme longevity pioneers. They've made their money in Silicon Valley. And with their technology solutions - PayPal, Facebook, cryptocurrencies - they've ushered in the world that we live in today, with all its unintended consequences. Some of them now want to solve the "problem" of aging, or even death, and they are making bigger strides than we may think.

Can they? Should they?

A Pillowfort production for BBC Radio 4

New episodes released Mondays. If you're in the UK, listen to the full series of Intrigue: The Immortals first on BBC Sounds: bbc.in/3WEQS5W

Vitalek Buterin is the billionaire founder of Ethereum, one of the most successful blockchains and cryptocurrencies in the world. With his fortune, he is attempting to solve the problem of death by creating a longevity state - which will fast track life everlasting, without the need for regulation.

They will crowdsource their longevity solutions and organise them through the blockchain. His north star is the Fable of the Dragon Tyrant.

In this series, technology reporter and psychologist Aleks Krotoski explores the frontiers of the extreme longevity pioneers. They've made their money in Silicon Valley. And with their technology solutions - PayPal, Facebook, cryptocurrencies - they've ushered in the world that we live in today, with all its unintended consequences. Some of them now want to solve the "problem" of aging, or even death, and they are making bigger strides than we may think.

Can they? Should they?

A Pillowfort production for BBC Radio 4

New episodes released Mondays. If you're in the UK, listen to the full series of Intrigue: The Immortals first on BBC Sounds: bbc.in/3WEQS5W

Many of the longevity innovators in the Valley want to extend human life. But there are others who are trying to eliminate death. A lot of them.

The tech billionaires who have never been told ‘no’ are driven to tackle the most insurmountable problems. They believe they can solve death by re-engineering the human in code. Problem is, it’s unlikely to happen in their natural lifetime.

But technology is on their side. Every year, computing power doubles. Once a decade, the amount of change produces a whole new paradigm. And that is what they’re banking on.

Science, combined with the rapid acceleration of technological change will keep them alive decade on decade until such time as they can achieve ‘longevity escape velocity’ - eternal life.

In this series, technology reporter and psychologist Aleks Krotoski explores the frontiers of the extreme longevity pioneers. They've made their money in Silicon Valley. And with their technology solutions - PayPal, Facebook, cryptocurrencies - they've ushered in the world that we live in today, with all its unintended consequences. Some of them now want to solve the "problem" of aging, or even death, and they are making bigger strides than we may think.

Can they? Should they?

A Pillowfort production for BBC Radio 4

New episodes released Mondays. If you're in the UK, listen to the full series of Intrigue: The Immortals first on BBC Sounds: bbc.in/3WEQS5W

Loyal for Dogs is one of the companies in the longevity industry doing serious science. They are well-founded, have a killer team, and a very clear mission: to be the first to get a drug that treats ageing - not just the diseases of ageing, but ageing itself - to pass the rigorous Food and Drug Administration approval process.

Their CEO, Celine Halioua, is a maverick founder whose life has been guided by her ability to work systems. So, to meet her mission, she’s got a hack that will get her new ageing drug into trials. That will be a first for the longevity community, and the foundation stone for the next phase of our search for eternal life.

In this series, technology reporter and psychologist Aleks Krotoski explores the frontiers of the extreme longevity pioneers. They've made their money in Silicon Valley. And with their technology solutions - PayPal, Facebook, cryptocurrencies - they've ushered in the world that we live in today, with all its unintended consequences. Some of them now want to solve the "problem" of aging, or even death, and they are making bigger strides than we may think.

Can they? Should they?

A Pillowfort production for BBC Radio 4

New episodes released Mondays. If you're in the UK, listen to the full series of Intrigue: The Immortals first on BBC Sounds: bbc.in/3WEQS5W

Jesse Karmazin’s Ambrosia Plasma clinic promised the fountain of youth, two litres of young plasma at a time.

For a fee, anyone could go to his treatment centre in the redwood forest outside Silicon Valley and receive an infusion. The results - according to Karmazin - were remarkable. Silicon Valley billionaires were rumoured to be queuing up for their young blood.

The problem was, the scientists whose work in mice he claimed to be bringing to the people disagreed with what he was doing, and he never backed up his claims with data. A journalist stepped in to investigate, and what she found was Silicon Valley hype without any substance.

In this series, technology reporter and psychologist Aleks Krotoski explores the frontiers of the extreme longevity pioneers. They've made their money in Silicon Valley. And with their technology solutions - PayPal, Facebook, cryptocurrencies - they've ushered in the world that we live in today, with all its unintended consequences. Some of them now want to solve the "problem" of aging, or even death, and they are making bigger strides than we may think.

Can they? Should they?

A Pillowfort production for BBC Radio 4

New episodes released Mondays. If you're in the UK, listen to the full series of Intrigue: The Immortals first on BBC Sounds: bbc.in/3WEQS5W

The Conboys’ experiment gave a young Harvard medical school graduate a big idea. But, there is a big gap between the experiments they did with mice in the lab, and pumping young blood into human beings.

Still, he registered his company, Ambrosia Plasma, on the Food and Drug Administration clinical trials website and began an ambitious human research experiment. For $8,000 in cash, cheque or digital transfer, anyone over the age of 35 could receive two litres of blood plasma from 16-25 year olds in their veins. The outcomes were ambitious - physical rejuvenation, weight loss, reversal of dementia, and healthy looking skin.

Does this fairy tale have a happy ending?

In this series, technology reporter and psychologist Aleks Krotoski explores the frontiers of the extreme longevity pioneers. They've made their money in Silicon Valley. And with their technology solutions - PayPal, Facebook, cryptocurrencies - they've ushered in the world that we live in today, with all its unintended consequences. Some of them now want to solve the "problem" of aging, or even death, and they are making bigger strides than we may think.

Can they? Should they?

A Pillowfort production for BBC Radio 4

New episodes released Mondays. If you're in the UK, listen to the full series of Intrigue: The Immortals first on BBC Sounds: bbc.in/3WEQS5W

Mike and Irina Conboy are a couple of tie-dye clad scientists in the bio-engineering department at the University of Berkeley. When they started researching ageing more than 20 years ago at Stanford, the field was nothing more than a spin-off from geroscience - most of their time at the lab bench was spent documenting signs and signals that our bodies are reaching their ends.

But in 2005, they published an article in Science that suggested there is hope for reversing ageing our tired old bodies. And the best bit of their study was that they proved there’s ample supply of the base material to do it - young blood. Using a revolutionary but ancient technique, their results re-ignited the millennia-old search for life everlasting.

In this series, technology reporter and psychologist Aleks Krotoski explores the frontiers of the extreme longevity pioneers. They've made their money in Silicon Valley. And with their technology solutions - PayPal, Facebook, cryptocurrencies - they've ushered in the world that we live in today, with all its unintended consequences. Some of them now want to solve the "problem" of aging, or even death, and they are making bigger strides than we may think.

Can they? Should they?

A Pillowfort production for BBC Radio 4

New episodes released Mondays. If you're in the UK, listen to the full series of Intrigue: The Immortals first on BBC Sounds: bbc.in/3WEQS5W