What do you do when a death looks suspicious, the official story does not quite add up, and the only place left to look for answers is at the bottom of the sea?

That is the problem at the heart of Dead Men Tell No Tales.

Across more than a century of British history, people have vanished from lighthouses, yachts, submarines, warships and fishing boats, sometimes leaving almost nothing behind. In other cases the evidence survived, but the truth became tangled up with rumours, government secrecy, strange coincidences and theories that refused to disappear.

There are the three lighthouse keepers who vanished from the Flannan Isles. Donald Crowhurst, whose boat was found drifting across the Atlantic without him. Robert Maxwell, discovered dead and naked in the sea after disappearing from his yacht. Lionel Crabb, sent beneath a Soviet warship on a secret British intelligence mission and never seen alive again. There are lost submarines, unexplained explosions, Cold War secrets, wrecks discovered decades later and a fishing boat genuinely dragged beneath the water by a nuclear submarine.

Then there is Bayesian, the luxury yacht that sank off Sicily in 2024, killing British technology tycoon Mike Lynch just weeks after his acquittal in one of the biggest fraud trials in recent history. His co-defendant died in a completely separate incident only days apart.

Some of these stories have perfectly convincing explanations. Others remain genuinely uncertain. In several cases the authorities really did keep secrets, while in others the evidence recovered years later destroyed the conspiracy theories completely.

And occasionally, the thing that sounds most unbelievable is the thing that actually happened.