When the new couple in town, both ex-cons, are suspected of murdering a cop’s daughter, they set out to entrap who they believe is the real perpetrator – before the town’s mass hysteria turns violent.

I think there is more of a hook if you were to change it from a “Cops daughter” to someone more high ranking such as the daughter of the Mayor, Commissioner, respected rich landlord etc. Also this adds to the other question, why not just leave? They are new to this town to start anew before shit hits the fan, so why stay here? It might work better if it was their hometown.

“A newly engaged couple, both ex-cons, return to their hometown, but when they are suspected of murdering the mayors daughter, they set out to entrap the real killer ? before the paranoid townsfolk lynch them.”