Tonight’s Once Upon a Time season 4, episode 14 exhausts every option to protect secrets from the past and discover new information to unlock the future.

Leave no stone unturned. That is the saying that will drive Mary Margaret and David deep into the mines to ensure their secret stays a secret on tonight’s Once Upon a Time season 4, episode 14, “Unforgiven.” But their past is not the only one that holds powerful information.

Previously on ‘Once Upon a Time’

Never underestimate the cunning nature of Rumpelstiltskin. Though banished and powerless, the Dark One still manages to cause a hassle in Storybrooke after feeding Belle a spell to not only release the fairies from the Sorcerer’s hat, but also the Chernabog. This demon sought out the heart with the greatest potential for darkness and it looks like Emma might be giving Regina a run for her money this season.

With Ursula retiring from a life feeding fish and Cruella leaving behind her husband’s financial ruin, the group convinces Regina to let them cross the town line and a new age of darkness falls upon Storybrooke.

Related: Four teasers for Once Upon a Time season 4, episode 14

This week on ‘Once Upon a Time’

Mary Margaret, David, and Hook, arguably three out of four of the most important people in Emma’s life, are desperate to keep their prior encounters with the Queens of Darkness buried in the Enchanted Forest. Regina, however, looks to the past to conjure up some clue hidden in the storybook.

Before Maleficent is resurrected from her dragon dust, test your knowledge of the Queens of Darkness in our Once Upon a Time quiz!

Once Upon a Time quiz: How well do you know the Queens of Darkness?

Watch Once Upon a Time season 4, episode 14, “Unforgiven,” tonight at 8:00 p.m. ET on ABC.