Board Thread:Show-Related Questions and Answers/@comment-24243167-20131224102233/@comment-25926288-20151201042802

Have you seen episode 3x15? Neal ressurected Rumple by sacrificing his life unwittedly.

Think of it like this. Rumple and Pan die and go to the Underworld. When the vault key is used, the Darkenss sucks Rumple's soul back to life and out of the Underworld.