“Secrets, secrets are no fun. Secrets, secrets hurt someone.” That was the theme in “Once Upon a Time” Season 4, episode 13 on Sunday. The episode was titled “Unforgiven,” and viewers learned Mary Margaret (Ginnifer Goodwin) and David (Josh Dallas) are not the “Charming” couple everyone believes them to be.

Episode 13 kicked off with Mary Margaret suffering from a nightmare. She dreamed Maleficent (Kristin Bauer van Straten) was alive and wanted to make her and David “pay” for what they did.

“When I’m finished you won’t have a family left to hurt,” Maleficent warned her.

Fortunately it was a dream, but David was just as uneasy about Cruella de Vil (Victoria Smurfit) and Ursula (Merrin Dungey) being in town. He believed the two were up to something and wanted to drive them out of Storybrook before anyone else found out about their dark secret.

Their first thought was to turn to Regina (Lana Parrilla) for help. But surprisingly she wasn’t interested -- even though Cruella and Ursula totally embarrassed her in front of Henry (Jared S. Gilmore). Instead she told David if he really felt it necessary, it should be the sheriff's department’s job to trail the two villains. Regina had better things to do, like continue looking for clues in the storybook about the mysterious author.

While Regina and Henry looked through the book, David enlisted Emma’s (Jennifer Morrison) help in trailing Cruella and Ursula. The pair paid a visit to Gold’s (Robert Carlyle) pawnshop where they made awkward small talk with Belle (Emilie de Ravin) about what a mess Gold was after getting exiled from town. Cruella claimed she was in the store because she wanted a hood ornament for her car, but in reality Ursula was loosing her tentacles to steal a mysterious box off a counter.

The villains thought they were being sneaky, but Belle knew her clutter. Although she didn’t know what exactly was in the box, she was able to warn David and Emma that it was stolen. David pulled Cruella over and inspected the car. He discovered the box in a hidden compartment, and found a magic token that previously belonged to Maleficent. He pretended not to have found anything and let them go. However, the token signified a big problem -- the two wanted to bring Maleficent back from the dead.

David and Mary Margaret began to freak out even more. Meanwhile, Regina was having a meltdown over the author situation. After talking to Mother Superior (Keegan Connor Tracy) last week, Regina and Henry hit another dead end. However there was one person that could have answers about the mysterious writer -- August (Eion Bailey). August was the only person who was able to insert a story into the storybook. Unfortunately August was no longer around, but his fairytale counterpart was. In the Enchanted Forest, August was Pinocchio (Jakob Davies).

Marco (Tony Amendola) and Pinocchio paid Regina a visit, but Pinocchio didn’t remember anything about his life as August. This frustrated Regina, and she lashed out at the young boy.

“Is that head of yours still made of wood?” she demanded. That didn’t sit well with Marco. He took Pinocchio and left.

Regina realized her mistake and paid Marco a visit. She apologized and acknowledged that although she’s frustrated, she can’t revert to her old, evil ways. Marco accepted her apology, and handed over August’s old bag which could potentially hold a clue about the author.

While Regina seemingly caught a break, David and Mary Margaret fell into a trap. They decided to head into the old mines to collect Maleficent’s remains. They thought if they got their hands on what was left of Maleficent, then the other Queens of Darkness couldn’t try to bring her back. But what they didn’t realize is that Ursula and Cruella wanted them to show up in the mines. Ursula knocked the two unconscious and Cruella used a knife to cut their hands. With their blood, Maleficent was able to rise from the dead.

So, what exactly was the dark secret that Mary Margaret and David were holding onto the whole episode? In a flashback to the Enchanted Forest of the past, viewers discovered the Queens of Darkness turned to Prince Charming and Snow White for help after Regina stole the dark curse from Maleficent -- the same curse that ultimately brought everyone to Storybrooke. Since the curse would affect Maleficent, Ursula and Cruella, the three villains decided they needed back up. They revealed to Charming and Snow a magical tree had the ability to reveal how to stop the curse. The catch was that it would only give the answer to two heroes.

With no other ideas on how to stop Regina, Snow and Charming agreed to team up with the Queens of Darkness. However, the trust still wasn’t there. When they got their first opportunity to run, the pair went to the tree by themselves. Placing their hands on a stone, they requested help from the tree. But it didn’t work. Magic shot the pair backward.

It turns out Snow was pregnant, and the product of true love can be unreliable. While their child could turn out to be a powerful hero, it could also turn out to be a villain “darker than anything” that the realm had ever seen. That was why the tree couldn’t help.

Since Charming and Snow were no help to them, the Queens of Darkness left -- but Maleficent later paid Snow a visit. She revealed that she too was expecting, and was afraid for her child’s safety. She once again suggested they team up, but Snow refused because she didn’t want to corrupt her unborn baby.

That wasn’t the terrible thing that they were trying to hide though. The big secret was that she was responsible for Maleficent losing her child.

Episode 13 of "Once Upon a Time" concluded with Belle kissing the Knave (Michael Socha), Henry discovering a picture of the author's door and Mary Margaret asking Regina to go undercover as a villain to stop the Queens of Darkness.