On the night of the 19th of April, 1956, the decorated navy diver Lionel Crabb went missing. A veteran of the Second World War, Crabb had been sent on a secret mission by MI6 to investigate a Soviet cruiser in Portsmouth Harbour. After pulling on his diving gear and checking his oxygen supply, Crabb slipped into the dark waters, never to be seen alive again. Was he killed by the Soviets? Was he killed by the Brits? Or can this all be chalked up to a bewildering accident? To this day, the government refuse to declassify the crucial files relating to his death. Dan is joined by Giles Milton, a writer and host of the podcast Cover Up: Ministry of Secrets, to untangle this mysterious web and find out what really happened to the frogman Lionel Crabb.

Produced by James Hickmann and edited by Dougal Patmore.

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