cliffhanger
1. An ending of a piece of fiction (e.g., a television episode, chapter of a book, a film, etc.) characterized by a dramatically suspenseful and uncertain end. A good summer book always has a cliffhanger at the end of each chapter so that you never want to put it down! Judging by that movie's cliffhanger, I'd say we'll be seeing a sequel coming out fairly soon.
2. A serial television or film production characterized by such endings. That show is a cliffhanger—the episodes never really have endings.
3. Any contest, competition, or other such situation in which the outcome is suspenseful and uncertain until the very end. The two teams have been neck and neck for the entire second half, and with two minutes left this match has become a real cliffhanger. This election is looking like a cliffhanger, and we won't be able to truly say who's won until all the votes are counted.