The Vikings were among the fiercest warriors of all time. Yet only a select few carried the ultimate weapon of their era: the feared Ulfberht sword. Fashioned using a process that would remain unknown to the Vikings' rivals for centuries, the Ulfberht was a revolutionary high-tech tool as well as a work of art. Considered one of the greatest swords ever made, it remains a fearsome weapon more than a millennium after it last saw battle. But how did Viking sword makers design and build the Ulfberht, and what was its role in history? Now, NOVA uses cutting edge science and old-fashioned detective work to reconstruct the Ulfberht and finally unravel the "Secrets of the Viking Sword."

A remote, bleak speck of rock in the middle of the Pacific, Easter Island, or Rapa Nui, has mystified the world ever since the first Europeans arrived in 1722. How and why did the ancient islanders build and move nearly 900 giant statues or moai, weighing up to 86 tons? And how did they transform a presumed paradise into a treeless wasteland, bringing ruin upon their island and themselves? NOVA explores controversial recent claims that challenge decades of previous thinking about the Islanders, who have been accused of everything from ecocide to cannibalism. Among the radical new theories is that the islanders used ropes to "walk" the statues upright, like moving a fridge. With the help of an accurate 15-ton replica statue, a NOVA team sets out to test this high-risk, seemingly unlikely theory—serving up plenty of action and surprises in this fresh investigation of one of the ancient world's most intriguing enigmas.