They bury Dren because they thought she was dead, but then she becomes male and escapes. He (Dren) randomly kills a few dudes (because all males are violent, apparently) and then he chases Sarah Polley and positions himself on top of her. While saying the words "inside you" he rips her pants off with his tail and shortly rapes her, before Adrien Brody saves her (he dies though). Then at the end of the movie Sarah Polley is pregnant of Dren and is seen selling her baby/research to a soulless evil corporation, hinting at a possible sequel with hopefully more graphic rape scenes.