 " Underneath " was written and directed by executive producer John Shiban . This marked his directorial debut . According to Shiban , part of the inspiration for the episode was that the series production staff had " actually talked for some time about doing a Jekyll / Hyde story but never quite found a way to do it " until the idea to use DNA came into play . Another inspiration for the episode was the 1949 film The Third Man , which featured a climactic chase through a sewage system . 
 " Underneath " was written and directed by executive producer John Shiban . This marked his directorial debut . According to Shiban , part of the inspiration for the episode was that the series production staff <a href='been_done' title='1'><mark>had</mark></a> " actually talked for some time about doing a Jekyll / Hyde story but <a href='None' title='2'><mark>never</mark></a> quite found <a href='None' title='3'><mark>a</mark></a><a href='negative_concord' title='4'><mark>way</mark></a> to do it " until the idea to use DNA came into play . Another inspiration for the episode was the 1949 film The Third Man , which featured a climactic chase through a sewage system . 
 Underneath  was written and directed by executive producer John Shiban . dis marked his directorial debut . According to Shiban , part of da inspiration fa the episode was dat tdaseries production staff done " actually talked for sum time about doing a Jekyll / Hyde story but don't never quite found no way to do it " until the idea to use DNA came into play . Another inspiration ffirthe episode was thda949 film Thedaird Man , which featured a climactic chase thru a sewage system .