In flashbacks, Ruby and Mulan find themselves in Oz, where they meet Dorothy. When the tree of them witness Zelena's return to Oz, they look for a way to defeat her once and for all. However, Dorothy mysteriously disappears, and Ruby's search for her new friend lands her in the Underworld. There, Ruby teams up with Emma, Regina and Snow to continue looking for Dorothy. Meanwhile, Snow and David struggle with not being with their son, Neal, and devise a plan so that one of them can escape the Underworld.
—Jennifer Percopo