The Devil and the Deep Blue, which premiered at the Tribeca Film Festival Thursday night, features a collaboration between star and producer Jessica Biel and her husband Justin Timberlake, who served as the movie's composer. Also making an appearance in the film? Their then-unborn child. Biel was nearly eight months pregnant when she made the movie. The story, about a grieving New Orleans architect (Jason Sudeikis) who helps a teenager (Maisie Williams) build a raft made of scrap material, was a passion project for Biel. She, along with director Bill Purple, worked for nearly 10 years to get it made. In the film, Biel plays Penny, the wife of Sudeikis' character. Penny dies in a car crash early on in the film. Biel and Purple had wavered on whether to make her character pregnant in the script, but then Biel's personal life intervened. "As it really started to become real, then I looked at Bill and I was like, 'Bill, I am really pregnant. What are we going to do here?' He was like, 'Well we can’t shoot around it. We should just go with it,'" Biel told Refinery29. That led to what Biel described as an "unusual working experience" for her. "I really had this kind of natural mama bear, like I want to go home and nest my world," she said. "You really do go through that thing where you just want to be home like knitting things, doing weird things that you would never do. At the same time, I really wanted to be on set because this was our baby." Metaphorically, of course. Biel spent three weeks on set, filming for only one. She returned to Los Angeles just as her doctor's no-fly deadline closed in on her. "It was a very strange thing to be far away from it all when it was going down, but also at the same time I couldn’t think about being on my feet any longer and trying to remember my lines and also be calm for my body," she said. "I see why women don’t work in that capacity when they are really, really pregnant, because it’s a lot of strain on the body and mentally weird." Biel gave birth to son Silas in April 2015. Timberlake was also personally invested in the film even before Biel and Purple were certain it was going to happen. "He loved the story and initially approached me saying, 'Hey, it would be cool to do the score on something like that,' I think maybe not knowing if it would actually ever happen," Purple said. "Then when it became real, we were like, 'So remember when you would be interested in doing the score?' And he jumped at it. He was like, 'Yeah, it would be great.' I think he’s the type of person that, put a challenge in front of him, he’s excited, he runs at it." Biel said she and Purple didn't "micromanage" Timberlake. "He speaks another language than we do," Biel said. "It’s like math. He’s like doing math equations back in the back room." The Devil and the Deep Blue Sea screens four more times at Tribeca.