What happens when you combine an axe-wielding microbiologist and a disease-obsessed historian? A strange brew that's hard to resist, even for a modern day microbe.

In the war on devilish microbes, our weapons are starting to fail us.  The antibiotics we once wielded like miraculous flaming swords seem more like lukewarm butter knives.

But today we follow an odd couple to a storied land of elves and dragons. There, they uncover a 1000-year-old secret that makes us reconsider our most basic assumptions about human progress and wonder: What if the only way forward is backward?

Reported by Latif Nasser. Produced by Matt Kielty and Soren Wheeler.

Special thanks to Steve Diggle, Professor Roberta Frank, Alexandra Reider and Justin Park (our Old English readers), Gene Murrow from Gotham Early Music Scene, Marcia Young for her performance on the medieval harp and Collin Monro of Tadcaster and the rest of the Barony of Iron Bog.

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Leadership support for Radiolab’s science programming is provided by the Gordon and Betty Moore Foundation, Science Sandbox, a Simons Foundation Initiative, and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.