Olivia and her sister Georgia are looking forward to a Cornish holiday filled with sand, surfing and fish and chips. Instead, soon after arriving at their seaside cottage, the girls stumble across a old smugglers' tunnel hidden behind a wall. They start exploring deep underground and are transported back in time, in the thick of a magical and dangerous adventure. Their world collides with the smuggling era of the 1700s when they meet Joey, a boy...