Bullfrog Films presents ; produced by Christopher McLeod, Robert Lewis ; written and directed by Christopher McLeod ; a production of Earth Image Films for Nova ; WGBH Educational Foundation
a FRONTLINE co-production with Mongoose Pictures in association with the BBC ; written and directed by Dan Edge ; produced by Dan Edge and Christopher Buchanan
Bullfrog Films presents ; A production of Earth Image Films for Nova ; WGBH Educational Foundation ; Producer, Christopher McLeod, Robert Lewis ; writer/director, Christopher McLeod ; for NOVA, senior producer, Kathleen Bernhardt