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.

To see more images and details about the series, vist the website here.

In the summer of 2022, investigative journalist Kirsty Johnston saw an email in her junk folder with an intriguing subject line: "Investigating the possible murder of my mother"

The message came from Sarah, a New Zealand woman living in the UK who'd been adopted at birth from Porirua Psychiatric Hospital.

Now in her mid-30s, Sarah had mustered the courage to contact her birth family, only to learn that her biological mother, Nellie, had died years earlier in what her biological aunt and cousins believed to be suspicious circumstances.

Sarah was left with unanswered questions. Who was her birth father? Why was Nellie admitted to Porirua Hospital in the first place? How did she truely die?

In this eight-part RNZ podcast, Sarah and Kirsty work together to uncover Nellie's story.

Go to this episode on rnz.co.nz for more details