In season 3, we have gone to Neverland and Oz, and this Sunday, will be the season finale of season 3. This 2-hour episode will begin at 8:00-10:01 p.m., ET on ABC. In the last episode, Kansas, it had ended with the green smoke from Zelena's body when she had been killed by Rumple even after he had promised Belle he wouldn't. The smoke had traveled to the area that which the portal would open.
Preview this finale at http://abc.go.com/shows/once-upon-a-time