 " TS @-@ 19 " was directed by Guy Ferland and written by Frank Darabont and Adam Fierro . Actor Noah Emmerich made a guest appearance on the show , portraying the character of Edwin Jenner , one of the few remaining medical personnel dedicated to eradicating the virus . Emmerich 's appearance was formally announced in November 2010 . Darabont foreshadowed the development of the episode the same month , alongside predecessors " Vatos " and " Wildfire " . " Before it 's all said and done , the opinions and actions of the group are divided . " Producer Gale Anne Hurd added , " Stakes are higher , dissension develops , rivalries intensify . " 
