 " Extinction " is the fifty @-@ fifth episode of the American science fiction television series Star Trek : Enterprise , the third episode of season three . It first aired on September 24 , 2003 , on the UPN network in the United States . This was the first episode following the addition of the prefix " Star Trek " to the title of the series . Set in the 22nd century , the series follows the adventures of the first Starfleet starship , Enterprise , registration NX @-@ 01 . 
