Just how dark will Mary Margaret get? That's the pressing question on the minds of most fans following last week's emotional Once Upon a Time episode.

And while viewers will see this heroine be tempted once again on Sunday's "The Miller's Daughter," they'll also spend time with The Dark One. A younger version of The Dark One that is, as he interacts with a younger version of Cora, played by Rose McGowan.

In the following photos from the episode, we see these two strike a deal, while also get a look at Neal handling a sword in Storybrooke and Emma sneaking up on Regina from behind. Click around now and get an idea of what's to come:

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.