cliffhanger

noun2

1. •
   An ending or stopping point calculated to leave a story unresolved, in order to create suspense.

   • Back in the early 80s, the hit series Dallas kept the nation guessing with its season-ending cliffhanger "Who Shot J.R.?" — 2007
2. •
   An outcome which is awaited with keen anticipation, especially one which is delayed for a period of time or which is not known until the last minute.

   • This presidential election is such a cliffhanger. Will it be the rising star Dmitry "Obamovich" Medvedev? Or the veteran Gennady "McCainovich" Zyuganov? — 2008