Watch Secrets of the Underground Online

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. Read More

Watch Secrets of the Underground online. Featuring , Secrets of the Underground has 2 seasons and 16 episodes in total. It is available for streaming online in the UK on 3 services such as Apple iTunes and Google Play Movies. It is classified as Reality genre series and the average rating across the web is 1. The TV series was filmed in United States of America and was first aired on 2017. Read Less