 " 4 @-@ D " is the fourth episode of the ninth season and the 186th episode overall of the American science fiction television series The X @-@ Files . The episode first aired in the United States on December 9 , 2001 on the Fox network . It was written by Steven Maeda and directed by Tony Wharmby . The episode is a " monster @-@ of @-@ the @-@ week " episode , a stand @-@ alone plot which is unconnected to the mythology , or overarching fictional history , of The X @-@ Files . The episode earned a Nielsen rating of 5 @.@ 1 and was viewed by 5 @.@ 38 million households . It received mixed to positive reviews from television critics . 
