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.
| Title | Secrets of the Underground |
|---|---|
| Genres | Reality Documentary |
| First Air Date | 2017-02-14 |
| Last Air Date | 2017-12-16 |
| Episode Runtime | 01 Hours 00 Minutes |
| Total Season(s) | 2 |
| Total Episode(s) on All Seasons | 16 |
| Runtime | |
| Production Companies | Science Channel |
No cast information available.
