Emily (Emily VanCamp) might want to watch her back because it looks like Margaux (Karine Vanasse) is getting ready to stab it in episode 16 of “Revenge.” The hit ABC series returned last night after a monthlong hiatus, and you can bet the upcoming episode, "Retaliation," will be jam-packed with drama – specifically when it comes to the Emily vs. Margaux storyline.

Since Daniel’s (Josh Bowman) demise, Margaux has been on a mission to clear the name of her baby daddy – one that Emily tarnished to protect herself. Emily did throw Daniel under the bus following his death, but that didn’t mean she didn’t care about the man who sacrificed his life for hers. Ultimately that doesn’t change the fact that the world now sees Daniel as an attacker who was killed by Emily in self-defense – and that just isn’t OK with Margaux.

In episode 15, "Bait," Margaux attempted to seek revenge on Emily by using the dirt she found on Em to expose her true, wicked nature to the world. However, the scandalous scoop she found on her nemesis also would bring down her friend Jack (Nick Wechsler). When Jack learned Margaux’s plot, he used his nice-guy persona to his advantage: He gave her a bracelet (made by his child) that just so happened to be installed with a computer chip set to destroy the blackmailing video.

After the tape was terminated, Margaux promised Emily that she would find another way to attack by unveiling Em's weak spot. And according to the episode 16 synopsis, she may have found one sooner than she thought. “Margaux steps up her plans to take down anyone who stands in her way,” the summary reveals.

At the end of episode 15, audiences saw Margaux talking to Emily’s current beau, Ben (Brian Hallisay), regarding the whereabouts of his wife. Could this be the “weak spot” Margaux was talking about? If so, it wouldn’t be the first time Emily's enemy used one of her lovers as a way to hurt her. Maybe that’s why Em was so adamant about not starting a relationship with Jack.

Speaking of relationships, Natalie (Gina Torres) not only will be using her newfound fortune to aggravate Victoria (Madeleine Stowe) in the upcoming episode, but she’ll also be using David (James Tupper) as a pawn in her plan to get under Victoria’s skin. Natalie reportedly will invite David as her date to her lavish Fourth of July bash, the synopsis adds.

“Revenge” Season 4, episode 16, “Retaliation,” will air on ABC on Sunday, March 15, at 10 p.m. EDT.