No-one claims them and no-one attends their funeral. Others have lain dead and undiscovered for weeks, or even years, before they are found and relatives traced. Driven by a desire to find out more about these lonely individuals from the people who knew and loved them, Lucy Cohen's bittersweet first film pieces together two people's lives and asks how in crowded, hectic, connected, modern Britain it is possible for anyone to simply slip through the cracks and disappear.

The film tells the stories of two people who died on the same case files of the same coroner in Manchester and who are buried in the same graveyard. Opening with the image of yet another unattended funeral, Cohen uses the coroner's reports, painstaking reconstruction, online detective work, and good old-fashioned leg work to uncover stories of hidden lives.

Knocking on neighbours' doors, hanging out in the corner shop, tracking down contemporaries from university and hearing memories from school friends, Cohen paints a picture of real people, uncovering touching stories: the hard-working student dreaming of setting up his own business and the fashion- conscious girl who stood up to school bullies and played on the street.

"There is a common misconception that the elderly in our community die in circumstances where they might have little or no contact with relations or friends," says Manchester coroner Nigel Meadows. "But, in fact, the reality is that people of any age can die like that."

Each story starts with the discovery of a body. Lucy talks to the local lads who accidentally kicked a ball into a garden - only to discover 34 year-old Nigerian- born Akinyemi Akinpelu lying dead inside, as he had been for several months. "He had no bed sheets on his bed or anything – nothing at all," explains Mark. "And all his clothes were in suitcases on the floor as if he was just about to pack up and go." Nobody had noticed he was missing. Akinyemi's neighbour, Elaine, remembers him without irony as "a good neighbour... you didn't know he was there".

But behind the body lies the story of a real person. Akinyemi's college remembers a man who arrived from Nigeria with a suitcase filled with friend Femi, who did not know Aki had died until Cohen told him, £10,000 in university fees, driven by an ambition to make the best
of himself:

"I remember when we were having a lecture there was a professor and he asked us where we would like in be in five years' time. Aki put his hand up and said in five years' time he wanted to go back to Nigeria and start his own engineering company. I thought, 'Wow, that's good'."

Following Akinyemi's many attempts across the years to get a degree, each time thwarted by his inability to afford the fees, Cohen wonders how affected he was by his failure to return to his family in Nigeria with the masters degree he came to the UK to study for. "His family, that keeps coming to mind," says Femi . "It's three years since he died, do they still think he is still alive? How can someone live in these circumstances? Somebody will be looking for him somewhere."

A 44-year-old, Sandra Drummond, lay undiscovered in her Manchester flat for nearly a year. Cohen painstakingly recreates Sandra's bedroom from photos in the coroner's report, trying to uncover the woman behind the collection of skin care jars, magazines, dolls and a hot water bottle. But it is Sandra's school friends who give the most compelling portrait of her – the tall girl with a love of fashion, the girl who stood up to the bullies and was funny. Friend Kay remembers: "It upsets me now thinking about it. You don't even know if she suffered or if she was waiting for someone to come and save her. I think that I would rather remember her as that really sweet girl who was our protector. She was lovely and someone should have protected her."

"This can easily happen," adds Sandra's other school friend Alya. "It can happen to anyone".

Celebrating these lost lives, Cohen finds warmth, humour and touching stories far removed from the bleakness of a lonely death. And taking us back to their gravesides, Cohen pays her respects to those who died unnoticed – but who lived like the rest of us.

Watch me disappear, Channel 4, Friday, 7.35pm.