The actor who plays the titular killer on the Audience Network series chats with ET about the Stephen King adaptation -- plus watch an exclusive clip from the finale.
David E. Kelley and Jack Bender's chilling adaptation of Stephen King's 'Mr. Mercedes,' starring Harry Treadaway as the titular killer, draws to a close with an explosive finale airing Wednesday, Oct. 11 at 8 p.m. ET/PT.
