The last of the so-called 'lunatic asylums' closed only 20 years ago. They were founded on ideas of paternalism and social progress and survived on the basis they offered safety. In this special crossover with the Black Sheep podcast, William Ray and Kirsty Johnston look into their origins.

Kirsty tries to find out if Nellie did have another baby, and where that baby might be, but gets stuck in a kafkaesque nightmare of bureaucracy. Sarah reflects on her journey to find Nellie. We talk to a disability expert about what Nellie's story really means, and if things are better now.

Nellie's coronial file reveals more about her death - and her life. There are badly healed broken bones, a skin graft, evidence of a fall three days before she died in which she broke her nose. Was her death malicious? Or was it just neglect?

Kirsty and Sarah go to see Mavis, Nellie's sister, who tells them that she thinks Nellie was raped, which led to her breakdown and incarceration. Mavis tells Sarah about the day she was born, and how the family wanted to keep her but couldn't.

Sarah goes to meet Gordon. We learn that he can remember Nellie, and remembers being caught with her in the bushes. Gordon tells us about his time at the asylum, and Sarah takes him on an outing where they spend time together.

The mystery relative turns out to be Sharon, her father's sister. She decides to fly to Australia to meet her newly-discovered niece. Sharon tells us how her family was extremely poor and her mother, Thelma had all her children taken from her. Gordon, Sarah's dad, was one of those kids.

Sarah and Kirsty call in the big guns: DNA. A strong match comes up: a woman who shares 28% of Sarah's DNA. Is it Nellie's first child? Eventually, Fran, the genealogist, suggests the match could be an aunt, and Sarah works up the courage to send a message to this mystery relative.

Kirsty and Sarah start investigating from opposite sides of the world. We learn what it was like to live at Porirua, and fight through red tape to get Sarah's adoption records, which reveal more about Nellie's background.

Out of the blue, Kirsty receives an email from a stranger titled "Investigating the possible murder of my mother". The author is Sarah, a young woman who was born to Nellie Wilson in a psychiatric hospital in the mid-1980s in Wellington and secretly adopted out.

Kirsty Johnston follows Sarah as she hunts for her biological mother, who turns out to have been an institutionalised mental health patient in Porirua Hospital. And that's only the start of the story.