Where To Stream Secrets of the Underground Season 1 Episode 2
Mystery of the Serpent Mound
- Aired February 21, 2017
- 60 Min
- Rated 8.2
- Number 6 Of 16 Rated Episodes
Exploring mysterious tunnels beneath Denver's airport, capitol building and downtown to investigate rumors of a secret organization that operates below; in Ohio, trying to uncover the ancient secrets of a giant mound shaped like a serpent.