In "Arrow's" third season premiere, Sara Lance's unexpected death devastated Oliver, Laurel and the rest of Team Arrow. Since then, the tight-knit group has done their best to piece together the killer's identity and motivation, even going so far as to request help from "The Flash's" resident bio-engineer, Caitlin Snow. However, despite their best efforts, Arrow and company find themselves heading into their mid-season finale with very little to show in the way of progress.

This lack of movement hasn't sat well with Sara's lover, the League of Assassins member Nyssa al Ghul. Having already targeted Malcolm Merlyn until Oliver's intervention, in this week's episode, "The Climb," Nyssa returns, demanding answers and seeking payback -- no matter who gets caught in the crossfire.

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Ahead of the action-filled continuation of Nyssa's hunt for Sara's killer, Katrina Law spoke with CBR News about her character's thirst for vengeance, the continuing conflict with Oliver, why she'd love to see the Lazarus Pits introduced to the world of "Arrow," and how Nyssa's wild card personality makes her such a great character to play.

CBR News: When it was announced that Ra's al Ghul's daughter would be appearing on "Arrow," longtime Batman fans assumed it was Talia. What was the character breakdown for the audition?

Katrina Law: It was, "Lindsay: An elite warrior and ex-lover of Oliver's who has returned to Starling City to try and win him back. As beautiful as she is deadly, Lindsay is used to getting her way, so when Oliver refuses to rekindle their relationship, she vows revenge. If she can't have Oliver, no one can."

Needless to say, I was a little misled. I also didn't find out who I would be playing until TV Guide announced it and I happened to run across their tweet!

Nyssa isn't nearly as established in the comic books as Talia. Did you feel that gave you more freedom in bringing her to life?

One of my favorite aspects of playing Nyssa is the freedom of interpretation the writers and I have been able to have with her. She has only appeared in 19 comics, as opposed to Talia, who is very well established. Whoever is playing [Talia] is tied to the comic bible of who she fundamentally is. I am honored to be a part of the DC world, to be able to be the first to bring depth, cinematically, to an already-complicated character, and to further enhance the original vision that [writer] Greg Rucka had of Nyssa when he created her.

Nyssa is a fierce warrior and member of the League of Assassins, but her emotions for Sara Lance are very real. How did her relationship with Sara add another dimension to the character? How did Sara's death affect Nyssa?

Sara Lance is the love of Nyssa's life, and she would do anything for her. Before Sara abruptly arrived in Nanda Parbat, Nyssa lived a life that balanced on a knife's edge, her view of the world painted in black and white. Nyssa was very much under the rule of her father, Ra's al Ghul, and adhered to the strict and brutal guidelines of the League of Assassins. Sara showed Nyssa a side of life she never knew existed and taught her what it meant to be in love.

Sara's death has sent Nyssa on a trajectory that she never wanted to be on. She is suddenly suspicious of everyone, filled with rage and heartbreak and feeling helpless for possibly the first time in her life. She is suddenly at odds with her father and the League of Assassins, with their first priority not being the hunt for Sara's killer.

Roy believes he killed Sara. What would Nyssa do with that piece of information?

I feel as though Nyssa would have a very hard time believing Roy capable, in either heart or skill, of being able to kill Sara. But I do think she would tranq dart him one more time just for the fun of it.

On the other hand, Malcolm Merlyn suggested Ra's is responsible for Sara's death. Do you feel that has crossed Nyssa's mind?

Merlyn's attempt to plant a seed of doubt into the minds of Nyssa and Arrow was lost on Nyssa. She is all too aware of the deviousness and selfishness of Merlyn's motives. I personally feel that had Ra's al Ghul wanted Sara dead for the reason Merlyn gave, he would have done it a long time ago and with the League watching. But that's just my guess. The writers don't tell me much, as you can tell from my character's original breakdown.

Nyssa returns in the upcoming episode "The Climb." What brings her back to Starling City?

It's time to find out who killed Sara.

At this point, how would you describe her relationship with Oliver?

The Nyssa/Oliver relationship will always be complicated. Nyssa has come to respect Oliver as a warrior, and has come to terms with the fact that he once possessed Sara's heart. But as it goes with Nyssa, the League will always come first, and because of her respect for the Arrow, she would hate for him to ever be on opposing sides of the League's agenda. It would be such a shame to have to kill him.

Nyssa tends to punch, hit and kill first, and ask questions later. What kind of confrontations and action can viewers expect in "The Climb?" And what do you enjoy about those types of sequences?

I love that Nyssa is a wild card; you never know if she will be your friend or enemy on any given day. I enjoy the fact that she cannot be classified as a "good guy" or "bad guy." That gives her carte blanche to do as she pleases, within the parameters set out by the League, of course. In "The Climb," we will, yet again, see another side of Nyssa that hasn't been seen before. The deference she has towards her father and the dominion he has over her will be a fun relationship to watch.

Arrow's creative team tends to keep plot spoilers close to the vest. "The Climb" finally reveals who Sara's killer is. Without giving that identity away, how does Nyssa react? And what is she willing to do in the name of vengeance?

Vengeance and justice run parallel lines in Nyssa's world, and injustice needs to be exterminated. When Sara's killer is revealed, it doesn't sit well with Nyssa, but she is forced to accept the final outcome.

What else can you tease about the episode?

Shirtless men fighting on a hilltop.

Looking forward, are there any elements of Nyssa's comic book history you would like to see explored on "Arrow?" How would the introduction of Talia further shake things up?

In the comic books, Nyssa has, to put it lightly, volatile relationships with both Talia and Ra's al Ghul. I would love to see how they would handle the Nyssa/Ra's Al Ghul story, and if they would actually have Nyssa murder her father and become the leader of the League of Assassins. Or, if they would introduce the Lazarus pits and play out the sequence where Nyssa uses it on Talia for the purpose of brainwashing her.

They'd probably never go this in-depth for a recurring character, but it would be amazing if they did delve into the al Ghul family having lived for centuries via the Lazarus pits, because that would allow for some flashback scenes to Nyssa being in the Nazi camps, losing her family and being tortured. That would be just an amazing challenge to portray as an actor.

Outside of acting, you're involved with a charity, Kitt Crusaders, which is near and dear to your heart.

Kitt Crusaders is a non-profit animal rescue based out of Los Angeles that I have been helping with. I've been getting some celebrity friends of mine to pose with rescued kittens, and the turnout has been amazing. David Ramsey and Caity Lotz from "Arrow" have both posed for us. Emily Bett Rickards has agreed to pose with a kitty over the Christmas break. Candice Patton from "Flash," too. There's been Sean Gunn, Brian Tee and Michael Massee from the Marvel world, and the one and only Stan Lee. The artists sign the photos and all the profits go directly to saving, medically treating and finding forever homes for the rescued animals. If you want to check it out and help out a great cause, you can find us at www.kittcrusaders.wix.com/kittcrusaders. We also have a Nyssa photo for all you shippers.

As we speak, you're on set of another project. What is it, and what's your role in it?

Right now, I am filming a horror movie called "The Quieting," directed by Austin Reading. Once the film gets started, it is a juggernaut of fun and horror, and it has been so much fun, running around a creepy old house with my co-stars Tara Holt and Bryce Johnson. I play Izzy, a fun little chick with an edge and a big heart. I'm excited for people to see a less stoic side of me.