The Victoria 168 was a tuna vessel that set sail from Panama in August 2015. Fisheries observer Keith Davis was on it. But when the boat returned to shore a month later, he was missing. How could this have happened?

Keith had an unusual job. As an observer, he spent months at a time at sea, monitoring the catch on fishing vessels, and acting as an independent watchman. In his 16 years on the job, he gained a reputation for speaking out against fishing malpractices and the mistreatment of crew members.

New Yorker journalist Rachel Monroe takes listeners on an immersive journey on the perilous high seas, as she investigates what Keith may have seen on board the Victoria 168.

Keith’s case wasn’t a one-off. Other observers have been lost at sea under suspicious circumstances too. Over the last decade, they have been going missing at a rate of at least one per year. Rachel looks into some of their cases, shining a spotlight on the murky underworld of the global fishing industry.

Trying to find answers hasn’t been easy. From examining the last pages of Keith’s observer log to make sense of his final voyage, to actually travelling to Panama to retrace his last days on land, Lost At Sea explores every angle of the story, featuring interviews with other observers as well as Keith’s closest associates.

Rachel Monroe says: “As soon as I heard about this strange, little-known world that Keith inhabited, the world of fisheries observers, I was intrigued.

"Observers have to walk a difficult line: they live on fishing boats alongside the crew for months at a time, traveling hundreds of miles off shore, eating the same food and working the same gruelling hours. But they're not members of the crew. They're there to take scientific observations, and to report any wrong-doing. That puts them in an incredibly vulnerable position.

"Looking into Keith's inexplicable disappearance, and the mysteries surrounding other observers' deaths, helped me understand how risky this work can be - and why some people are drawn to it, despite the dangers."

Lost At Sea is available as a box set from 24 August on BBC Sounds.

Lost At Sea is a BBC Studios Podcast production for BBC Radio 5 Live and BBC Sounds. It is presented by Rachel Monroe. The series is produced by Monica Whitlock, with sound design and original music by Jon Nicholls. The executive producer is Paul Smith. The commissioning executive for BBC is Dylan Haskins.