McDonnell, who played Captain Raydor for three seasons on “The Closer,” spoke to THR about leading a new show, a possible Kyra Sedgwick appearance and what to expect in the coming episodes.

Mary McDonnell is now in charge.

The Closer may be over, but spinoff Major Crimes is keeping the wheels turning. The TNT drama, toplined by the Battlestar Galactica vet as Captain Sharon Raydor, launched after Closer‘s series finale earlier this month to huge numbers: 7.2 million viewers, to be exact. For McDonnell, who played Raydor for 26 episodes on Closer before jumping over, it was a “beautiful” sight to see.

“People understood what that big Monday night was going to be,” she told The Hollywood Reporter of theCloser series ender and Major Crimes’ debut. “People really prepared for it and it worked.”

McDonnell spoke to THR about going from a supporting player to being No. 1 on the call sheet, taking the reins from Kyra Sedgwick, a perfect scenario for a Sedgwick cameo and challenges leading a new show.

The Hollywood Reporter: You’re now leading your own show, taking the reins from Kyra Sedgwick. Was there any moment of hesitation?

McDonnell: No, there really wasn’t. To be perfectly honest with you, it evolved so organically. It was a natural evolution. The whole idea that it would blossom into more of an ensemble was also a part of the equation. On the one hand, I knew and was quite happy to carry the bulk and I loved James Duff’s writing and his mind — the transition of this character from antagonist to protagonist, which I’ve never done in my career — but I also felt very strongly about this whole group of people was a whole new show as well, I knew there was tons of story to be mined.

THR: Going from antagonist to protagonist, were there unexpected challenges for you?

McDonnell: It was challenging because when you’re clear about your function as a character in one form and you know that the next form is going to require you to open up other dimensions of the character, you have to constantly discipline yourself to make sure your movements are authentic. You can’t just bring someone into a “likable” position all of a sudden, you have to be true to the human being in the first incarnation. To me, it felt like a good pivot outward. It allows the audience to see someone who they saw through a certain lens, they’re now seeing through many lenses. They’re saying: Wait a minute, this woman has always had a group of people that she worked with for 30 years in Internal Affairs. She perhaps had a great department there. She has a way of working with people, that there’s more to her than what we’ve seen so far.

THR: With Captain Raydor now the head of the division, how does she adjust to her new position and how is she perceived by those who must report to her?

McDonnell: Something that she did that was very wise in the very beginning, she has a good wisdom in terms of management style. She understood why she was in that position, for bigger reasons than the politics of the moment. She understands full well that it isn’t going to be easy with the other people. She understands resistance. What I started to find out about her, having seen the squad to amazing work, she had knowledge of them as individuals more than they understood her. That allowed her to grow naturally in leaning on them and asking for their best, her understanding of how they have to do things. That allowed her to be a boss that they eventually could reassess.

THR: What is the toughest relationship for her to work on?

McDonnell: The relationship that brings the most resistance for very legitimate reasons is Provenza (G.W. Bailey) and that is a fantastically fun relationship for us to play. [Laughs] We get to really explore some places that we know what it is. She understands his point of view and the fact that she needs him to get over it, she still gets it. There is a very funny, moving relationship that begins to get explored between the two of them given this terrible situation. [Laughs]

THR: What is the most challenging situation that she finds herself in this season?

McDonnell: Captain Raydor gets the job done. Whatever the obstacle, she’s willing to confront it. She doesn’t back down, which makes for some interesting stuff I think.

THR: What can we expect from Raydor’s personal life as the episodes unfold?

McDonnell: You start to find out bits and pieces of the kind of life that she led and it’s actually rather full. We begin to know more about the way she lived, what she’s interested in and things about her family that we didn’t know before. You start to get the picture of a woman who’s got a rather full history and life.

THR: You’ve played this character for several years. Was there an aspect of Raydor’s character that surprised you as you filmed Major Crimes?

McDonnell: I was delightfully surprised by her ability to apply a broad understanding of a situation to the specific moment of resistance. She really does understand the politics of the day. She understands the law, police department, where it all fits and threads through. In The Closer, people would often refer to her as a rule follower. In fact, James immediately revealed — and I suspected this was true — what happens when you apply renegade tactics. And she can give it as good as she gets because she understands it. That was a delightful revelation to me.

THR: Is there a perfect scenario for Kyra to make an appearance on Major Crimes?

McDonnell: I don’t know what the perfect scenario would be, but I can’t imagine that wouldn’t be just fantastic. [Laughs] Wouldn’t it be great? It would be fantastic because the fans would go berserk. It would be a hot ticket item, there’s no doubt about it.