Just before he died, John Daniell's step-dad told him a secret from his time as a spy. A secret that was possibly New Zealand's biggest of the Cold War and that has never been revealed. Until now.

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In the midst of the Cold War, first John Daniell's mum and then his step-dad worked for New Zealand's Security Intelligence Service (SIS). Spies stayed in the spare bedroom. His step-dad went out on missions. And John kept secrets.

Over five episodes, John Daniell and his friend, RNZ journalist Guyon Espiner, search for the truth behind a family story that might just be one of New Zealand's biggest Cold War secrets.

For nearly a year John and Guyon have been investigating this closely guarded secret. Having spoken to former Prime Ministers, senior officials, experts on intelligence services and even former spies themselves, they can now reveal this never-before-told story.

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