When Norristown's Theatre Horizon's directors Erin Reilly and Matthew Decker began planning their 2016-17 season, they didn't expect to go through the tragedy that was the passing of Decker's mother. Hindsight being 20/20, perhaps they would not have opened on Oct. 20 with Decker directing "A New Brain," a darkly comic musical penned by James Lapine and William Finn that touches on Finn's experience with arteriovenous malformation and art's healing powers. Then again, Horizon and Decker (an upcoming Barrymore Award nominee for directing "The Stinky Cheese Man and Other Fairly Stupid Tales" at the Arden) don't do anything easy and welcome all challenges. They also welcome its star, Philly actor Steve Pacek, for his sixth show with the company, which has to be a record. Decker spoke enthusiastically about the upcoming production from the rehearsal rooms for "A New Brain."

You're going on 11 years at Theatre Horizon. How do you feel as if going into this newest season that you guys met then surpassed your aesthetic and personal goals?

I think in starting Horizon, Erin and I wanted to make high quality theater we were passionate about with a group of like-minded artists and audience members. We wanted to produce theater outside of Philly, because 11 years ago, we felt the city was over-saturated with companies. We wanted work to be high quality and professional with Philadelphia-based artists. I don't think we necessarily set goals to build a theater, or to settle in downtown Norristown, or to run a theater school and an autism drama program. Those paths revealed themselves organically. We just followed them.

What are you looking at when you decide to take on a play?

I simply have to ask myself if I connect personally with the story. As a director, you can spend up to one year of your life living with a play — thinking about the characters, the themes, the physical space. So the play must get under my skin in order for me to want to bring it to life. After doing this for 12 years, I know what it costs me to direct a play — the emotional and physical toll it takes on my heart and body, the sleepless nights during tech and previews, the long rehearsal hours, time away from family and friends. I really have to love the story to want to direct it — feel it deep in my gut.

Why pick "A New Brain"?

I'm a [William] Finn fan. I directed a production of "Spelling Bee" in 2010 at Theatre Horizon. I encountered "New Brain" when I was studying at NYU, and like the score. Then 11th Hour Theatre hired me to direct a concert version of it last year — with Steve Pacek as Gordon — and in revisiting the piece later in my life, I was struck by how deeply moving it is. We're asked to go through hell and back again with Gordon as he struggles with his brain injury. Along the way we're treated to that which illuminates the importance of actively making choices to live a life you want to live. We only get one shot — better make the most of it.

Where were you emotionally when choosing "A New Brain"? Where was your mother's health in relation to that choice? How much do you feel as if this tender scenario had to do with you choosing that play or making the directorial choices that you did?

My mother recently ended a 15 month battle with lung cancer. At the time we programmed "Brain," she was sick, but stable. We decided to do it because we liked it. Suddenly, mom took a sharp decline, and then boom — she was gone, and I had to direct a show that was all about a man who is facing a life-threatening illness less than six months after my mother's death. So, I almost quit the show four times. Couldn't figure out how to make it work. Couldn't listen to the score without crying. Couldn't read the play without feeling sick to my stomach.

Look, I worked through my mom's passing. Did you feel as if you had to work through this and was there ever that guilt pang that maybe you should slow your roll?

I ultimately decided I wanted to get back to work because I'm at my happiest directing a play, so it just felt right to return to something I love doing. I now understand what Gordon and his family are going through, for better and for worse. I always weep openly at its song "The Music Still Plays On" that Gordon's mother sings to him about their life together. For obvious reasons watching a mother sing to her son is difficult for me right now. My mother knew how much making theater means to me, so, I don't feel guilty in getting back to work. But at the same time, I'm in mourning — she passed in May. So I'm still figuring stuff out, giving myself permission to be a complete and utter mess while doing it. I'm trying to be kind to myself, take one day at a time, staying as present as I can. And to keep going.