Rob Bell explores the costal defence network that was put in place to defend Britain's beaches from invasion, including a tower in Essex which controlled mines laid across the estuary. In Freiston Shore, on the coast of Lincolnshire, he discovers some of the finest defence buildings still standing. Finally, he heads to Cuckmere Haven, in East Sussex, where seemingly random bits of concrete reveal an intricate network of defences.

Numerous pill boxes, gun emplacements and dragons teeth were all tactically positioned to slow the Germans trying to get to the major cities.