Readers beware: You might want to lock your doors this Halloween season if you don’t like bloodthirsty vampires or twisted fiends who set cruel death traps just for you. Or just stay out of the movie theaters.

Hollywood launched its first film of the fright-filled month with Friday’s release of “30 Days of Night,” a horrific vampire film starring Josh Hartnett. Hartnett dons the uniform of a brokenhearted cop who is forced into the role of a hero and confronts creatures that would make the bravest person’s skin crawl.

“30 Days of Night” incorporates the classic vampire phobia into its storyline, but focuses on a frightening new premise: a tiny Alaskan town cut off from all civilization by 30 days of complete darkness has all of its lines of communication destroyed by an evil force to prepare the way for an onslaught no mortal can stop, the gory massacre of an entire populace obscured by black shadows and feet of concealing snow.

Outstanding cinematography accentuated incredibly vivid special effects that highlighted every minute of gory death and mutilation down to the last sinew. Certainly not for anyone without a stomach of steel, “30 Days of Night” was splattered with enough blood to sufficiently cover up an unsatisfying explanation of character origins and relationships, both human and vampire.

“And what would Halloween be without Saw?” threatens the trailer for the latest installment in the cult series. “Saw IV” hits theaters Oct. 26 with the promise of sadistic indulgence in human terror and a cleverly concocted plot to drive the film along to its finish-until next year, anyway.