Heather Headley's warmth and generosity—and that voice!—are legendary. Which is why it may surprise you that she was cast as the resident baddie Dr. Gwen Garrett for the latest season of NBC's Chicago Med—the hospital-set drama of the Dick Wolf Chicago franchise that also includes Fire and P.D.

But Headley is back in Chicago (where she began studying at Northwestern before leaving school early to join the out-of-town tryout for Ragtime as an ensemblist and understudy for Audra McDonald’s Sarah) and revels in playing a new kind of character. “I know she's not loved right now and may never be. But the aim is to have the viewers and the characters in the show every now and then kinda look at themselves and go, ‘She’s right.‘”

The Tony winner for Broadway’s Aida first made her Main Stem debut as the original Nala in Disney’s The Lion King, and then waited 15 years (forging a career as Grammy-winning recording artist) before returning as the replacement for Shug Avery in the 2015 Tony-winning revival of The Color Purple. With Chicago Med, Headley now moves into television: This is her first network show and only second series overall.

What made you join the Chicago Med family?
Heather Headley: I really was excited about working with Dame E, as we call her, Epatha Merkerson, and, of course it's just a great franchise. [Gwen] can be a little meanie. As women, they call you the bad word. And most of the times it's not the case. It's just there's a job to be done. The way I see it is if she doesn't get this job done well, not only is she out of a job and everybody else in the hospital is out of a job, but the city is out of a hospital. I'm gonna try to bring some kind of [nuance] so people can see through that and maybe appreciate that about her. She’s fun to play even though she's so bad. Let's just say that I’m taking cookies to the set and, “Anybody want me to wash their car? I'll wash your car. I promise I’m really nice!”

Your TV career is still new. What's the most surprising element of acting on television or just the TV world?
Broadway’s a lot of work, don’t get me wrong. It’s eight shows a week. You hardly ever see the sunset. I remember when I left, I was like, "Oh! The sun's setting! I haven't seen that in a year!" Singing eight shows a week is hard. It's a different discipline. For the [theatre] shows, I walk in, let's say at 7:30, and at 11 o'clock I am leaving. Whether that went well or not. With television, it's like, "Do it again! Do it again from this angle! From that angle! From the other angle!" It's a constant, "Do it again. Do it again," and a lot of times you [need to look] the same. You have to remember your hands. Where were your hand before? So it's a completely different discipline. One scene can take two-and-a-half hours. Somebody was like, "I think being on Broadway is harder," and I was like, "Really? 'Cause I think the way you guys do it is a little hard."

Speaking of difficult things, what has been a challenging moment that stands out to you from your career?
That question is loaded for me because I think every challenging moment has led to something great or amazing. A challenging moment for me was the decision about leaving Ragtime to go to this show that was coming in called The Lion King and me thinking “Is it going to work?” Even the difficult moment of leaving school to go to Ragtime, but now I don’t see it as being that difficult. The decision about “Do you want to go do the albums?” or the decision about the right time to leave Aida. I never wanted to get to the point of looking at the audience and thinking, “I hate this! I’m ready to go!” The decisions themselves were the challenge.

You mention The Lion King, which you celebrated last year on its 20th Anniversary. It turns 21 next month. Is there one memory that still stands out to you?
I had left Ragtime—and Ragtime was a completely different beast, no pun intended, than The Lion King. And [The Lion King] is still one of my favorite shows in the whole wide world. In Ragtime I was supposed to be bright and then in Lion King [director] Julie [Taymor] was like, “I need you animalistic and we’re lions.” I remember coming into The Lion King and, oh forgive me Lord, but doubting it. The way that musicals are put together, we're kind of exclusive of each other. And so somebody's working on this in one room, and somebody's working that in the other room. I did not understand how all this was going to come together.

So, we were going to do a press performance. I remember the curtain popped up, that sun came up and Tsidii went, "Nants ingonyama!" And the cheetah came out, the giraffes came out and I kinda bent over. The only thing I could do was to grab Julie's hand. I grabbed it to the point that I'm sure she's got marks in her hand from my nails. I was like, "Hoo!" I can see the moment now. I just remember that moment of seeing that opening number for the first time and loving it and thinking to myself, "Oh, I'm a part of the greatest show ever."

You have concerts coming up in Philadelphia, New York, and in Boston. Can you tell us the song you'll never stop singing and you always love singing in concert? And then the new song that perhaps you haven't sung before in concert that you're excited for people to hear?
That's terrible 'cause they're all like babies. There are some days that it's "Somewhere Over the Rainbow." I have to sing it. I've now fallen in love with "My House," and I have to sing it. "I'm Still Hurting" and "For Good," they've kinda slipped in there for me. I love doing "I Will Always Love You." That little core group: my children.