Board Thread:Show-Related Questions and Answers/@comment-2153169-20151008095703/@comment-2153169-20151010175553

Broken Heart is the penultimate episode. 511 is the winter finale and 512 the 100/spring premiere. The double hour could be either a two-hour episode (which would be counted as one, like STM) OR it will be like the season 3/4 finale meaning they'll air 2 episodes so 2 eps.