Decades pass without an answer. But in 2020 lightning strikes. A BBC reporter gets a mysterious call – the man says he’s been deep within the police and he’s seen something that might blow the case wide open...

Presented by Suchin Mehrotra and Colin Campbell

Series written and produced by Satiyesh Manoharajah

Audio production, sound design and original music: Steve Urquhart

Executive producer: Alistair Jackson

A BBC Studios Production