An accountant gets more then she bargins for when she crashes into a staged relationship with a charming actor looking to salvage his flagging career.

Not sure what "crashes into a staged relationship" is supposed to mean.

The actor is "staging a relationship" for a specific objective goal: to salvage his career. If the accountant is the protagonist, what is her objective goal in getting involved with the actor? Why would she get involved with a failing actor? What does she stand to lose if/when the relationship fails?

At this stage, I think your concept just needs some clarification before it can be improved. What does the "getting more than she bargains for" look like? I'm confused by the action "crashes into" - how does this happen? Assuming she's the one who ends up in the relationship unwittingly, how is the relationship staged? That's the part that I find fascinating. I think you need to ask yourself, "what fascinates me about this logline?," and go from there.

Why an accountant? You might make a more powerful character choice. For example, if you make her a psychologist, then we immediately want to know, "how is this actor going to pull one over on a woman who's trained to spot BS?" And it forces him to become a better actor to keep up the lie.

I realize that I may have completely misunderstood your intentions, but this is where my mind went.