Two main characters and several ghosts

I'd like to ask for some opinions on this question. I have a supernatural thriller screenplay I'm seriously considering writing, but it has a pretty unusual structural limitation: it has only two living characters for nearly the entire story. There is the protagonist and someone you could think of either as an antagonist or a secondary protag, depending on your view of it.

There are several ghosts involved that have places in acts 2 & 3, and I guess they definitely count as characters, but not living ones. The ghosts won't have much conventional dialogue, I don't think. But they'll be playing a major role in the action. Basically they will be haunting the human characters and in doing so, revealing the story (backstory of the house and its prior occupants).

The question is, does the fact that there are only two living characters seem like it would be a limiting factor? I mean, I'm sure I can write it, but would it go against convention in a severe way? I wouldn't want to put all the work into writing something that I'm worried that any professional reader who reads it is going to react badly to the absence of the usual range and number of speaking characters. In other words, can two characters sustain a 90-minute movie?

The reason that there are only two characters is that according to the premise as it exists right now, they are forced unexpectedly by adverse circumstances to take shelter in a particular location as they're driving somewhere.

Any thoughts?

Thanks man, I was blanking out when I tried to think of some examples. You took care of that very efficiently.

I haven't seen any of the Paranormal Activity films. Do the ghosts in that have any story, or are they just making doors slam and beds move, etc.? What I like about my idea is that there's this really tragic story behind it, and the challenge will be to try to find ways to reveal that backstory through the "haunting events" that they cause. So I'm going to be visualizing creepy and tragic things that they do and ways for them to communicate, but I predict that it will be difficult to avoid visual cliches.

Thanks everyone. Very helpful.

I do now believe the story idea has merit, or should I say "potential," and will work if told right.

Actually, one reason I joined here (though certainly not the only one) is I would like to find a "spitballing partner" here if possible... someone to hash out plotting ideas with in PMs or email, in exchange for more of the same on their ideas when desired. I can offer input as well as take it. Sometimes that fresh approach by someone else is what's called for when you feel a little stuck, no?

Thanks gambit, that's a pretty good example, but try to imagine Cast Away if the story didn't end with Hanks going back home and all that, but had stayed on the island the whole time. That would be a closer analogy for my story.

Wait... then again, it just hit me like a ton of bricks that I could do a similar thing with my story and that I don't have to end it the way I was thinking (with only the two characters).

In fact, your mention of Cast Away has helped me a lot because I can now visualize a much better ending that uses a classic denouement instead of the "edgy" thing I was picturing until now. So thank you again!