About The Show
One of the best-kept secrets of the Second World War was a huge aircraft-carrying submarine designed to deliver Japanese bombers to within a few hundred kilometres of American cities. Engineers and historians conduct experiments and demonstrations to reveal the secrets behind a technological marvel that could have changed the course of the war. Plus, archive footage shows what made the I-400 subs so deadly: the three state-of-the-art attack bombers it could carry anywhere in the world. But why was the technology never used in an attack on the US?

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