The sneak peek begins with Charming (Josh Dallas) telling Snow (Ginnifer Goodwin) over the phone that the rest of their dysfunctional family is headed back to town. Unfortunately for them, Cora (Barbara Hershey) and Regina (Lana Parrilla) have a enchanted box phone tap set up, and overhear the whole conversation. How dastardly!
Even more dastardly is the "new" plan — though we suspect it was her goal all along — that Cora reveals.
Here's the deal: If Rumple dies without passing on the Dark One powers, the powers will disappear forever. Plus, Cora claims, he's too injured to do her bidding without risking said death.
Cora's conclusion? She'll just have to kill Rumple and take the Dark One powers for herself. Because that's totally what a loving mother whose only goal is to reunite her family would say. At least Regina seems to realize this is a step too far, based on her stunned expression as her mother unveils her evil vision.