Is this a good enough plot for a story or does it sound took much like something else?

Sounds very familiar, kind of like a mix between saw and law abiding citizen. But don't let it dishearten you. If you take your time and write the story well it will probably turn out fine, and most stories sound like something else. It is said that there are only 7 stories in the world, so its difficult to come up with something that doesn't remind you of another story.