The Guillermo del Toro produced Mama, starring Jessica Chastain (Zero Dark Thirty) and Nikolaj Coster-Waldau (HBO’s “Game of Thrones”), will make its Blu-ray and DVD debut tomorrow May 7, 2013. With that in mind I recently hopped on the phone with the film’s director Andy Muschietti and his co-writer Barbara Muschietti to discuss the challenges of turning a 3 minute short into a full-fledged feature. Their well-timed nugget of inspiration came as a surprise to me, to say the least.

The film “is the story of two vanished girls whose parents were killed. When the girls reappear, their uncle and his girlfriend care for them, but that doesn’t mean their deceased mother is completely out of the picture.”

Head inside for the interview, which includes a possible take on a Mama prequel.

This all started with a short. What’s the process of adapting that and teasing it out to a feature length like? You’ve created a rich story around it.

Andy: We weren’t thinking of expanding it when we shot it. The short was just a single idea, a sequence. There was no purpose other than an exercise of style. Because at that time we were writing a different movie called The Yearning that was visually in the style of that short. So the intention was to use it as a supporting piece for that movie, but then people started to ask us what the story behind it was. “Why are the girls running from Mama? Is it a ghost, is it a zombie?” So it had more of an intriguing effect than we thought.

So when we started stretching out the story there was an idea that I got from watching a National Geographic documentary that featured a Cheetah eating a Monkey. And as the Cheetah is eating the Monkey, the Monkey gives birth. And instead of eating the baby Monkey, the Cheetah starts taking care of it. And I watched that in the week we were trying to crack the story, so it was very helpful.

Was Del Toro’s role in this more to shield you from studio interference, or did he help you shape the building blocks as well?

Barbara: I think he did a little bit of both. He’s extremely respectful. He made it very easy for us to go into our first movie. He’s always saying he’s the kind of producer he would like to have. And that’s what he did, he gave us the freedom we needed and shielded us in quite a few circumstances. He is the best godfather you could have.

The ending seems to spark a lot of debate.

Andy: I don’t think we were prepared for that reaction. At the end, it’s inevitable to unmask her and reveal her motivations. But I’m extremely happy with the debate around the ending. It’s a bittersweet ending. It’s memorable, it’s not just a happy ending.

This movies did quite well, are you guys thinking about the sequel?

Andy: My instinct as a director doesn’t push me towards a sequel, but we are having conversations with the studio because a sequel might happen. I’m more driven to a prequel maybe, maybe something that tells the story of what happened before. There’s 150 years of Mama roaming the woods, looking for her baby. There’s this house, why was it abandoned? What happened to the family? It would be fun to explore that. Anything’s possible.