Screenplays and the Unreliable Narrator

Although I vowed to never again write (re-writes are okay) a screenplay because I think film as a medium for conveying a story is far too limited I've been toying around with an idea for a film or possibly a tv series for a couple of weeks now.

Right off the bat I've hit a snag as the initial opening scene is essentially unfilmable as I imagine it. Without giving too much away the opening scene takes place in a space without light so there's nothing to film. The only way to convey what's going on is to change this or have someone or the person involved narrate it which I don't like the idea of much.

I have an idea of how to tell what happens in the opening (maybe just use a black screen and some sounds during the opening credits) by someone coming into that dark space later on and bringing light with them or light pouring in after that space is opened. Then, retroactively we "get" what happened in there.

Anyways, aside from that I've been thinking about using the 'ol Unreliable Narrator angle for the film's leading heavy since it's a cast piece. There's some research involved but overall I think I can just write willy-nilly and then shore it all up in some re-writes. But the idea of a cast of Unreliable Narrators, plural, is something I've never really come across before. We'll see. I may start outlining it in the next few days.