Secrets of the Underground 2017

A search for an underground escape route said to have been used by Al Capone. Also: who or what built earthen mounds in Washington state.

  • Poster for Season 1

    Season 1

    2017

    8 episodes

    Season 1 of Secrets of the Underground premiered on February 14, 2017.

  • Poster for Season 2

    Season 2

    2017

    8 episodes

    Season 2 of Secrets of the Underground premiered on October 28, 2017.