Who else would like to write a screenplay?

It's a dream of mine to write one, even though I don't really know how to. I can write, I'm not the best writer, but I continue to improve. I currently have an idea and wonder if anyone would find it interesting/feasible. Looking at it, which audience do you think it would appeal to?Heres the basic plot:A psychopath has managed to escape from a high security mental institution, starting a new wave of murders, starting from Chicago not far from where he escaped and ending up in San Antonia on his way to Houston. In each city/town he leaves a body. His thirteenth victim is in Houston, though he hasn't gotten to the person yet. Afterwards he's headed down to Mexico. His own sister is a bounty hunter and since learning of his breakout she's been on his trail, working with her estranged husband who might just be an FBI agent. They're not the only ones on the case, there's a Mainecoon cat too, who belonged to the psychopaths first victim since breaking out who witnessed the last moments of her owners life. She is one determined cat, trying to help the bounty hunter and her husband catch the culprit.