This was a fantastic series which was aired on BBC Three recently. In 1996, a 16 year old boy called Damien Nettles went on a night out on the Isle of Wight, UK, and just disappeared. He's never been found dead or alive.
There's all sorts of rumours about what happened to him, but the trail has gone cold. Many people believe he wound up getting in trouble with local drug dealers, who killed and disposed of him. The police investigation was exposed as a shambles as they lost evidence, leaked files and tried to cover up aspects of the case. It's been compared to Making a Murderer by some.
This is the trailer of an 8-part series, each episode is 15 minutes long. I really recommend watching it. Here's the link to the playlist: