It's one of the most famous prehistoric monuments on Earth. A mysterious arrangement of stones that have adorned the English countryside for millennia. But to this day, nobody knows how the landmark was built or why. Can modern technology finally unlock its secrets? What is the true purpose of Stonehenge?

In 2016 a mysterious illness strikes dozens of government officials in Cuba. Over the next few years, hundreds more are afflicted. But investigations raise more questions than answers about this bizarre epidemic. What is the true cause of the strange phenomenon known as "Havana Syndrome?"