When a perfectionist hitman kills the wrong man he has only two hours to find out what went wrong before the Mob can take its brutal revenge.

The log line is giving us what we need to know but I do suggest a few minor changes. I agree with the perfectionist description as it doesn't feel very fitting. I would also maybe change the wrong man to wrong target, simply because you use the term man two words before and makes it sound a little odd (this is my thing really). Other than that it is coming on but still think there is a way to tighten it. Perhaps look at the line 'find out what went wrong', a little generic and think you can find a better phrase or a better task.

Pretty close - but I have two niggling little issues:

The final part "the Mob can take its brutal revenge" suggests that in two hours, the Mob will have the chance to take their revenge. If you reword it to "the Mob takes its brutal revenge," it makes it a foregone conclusion. If he stuffs up, they'll kill him. Plus you drop a word from the word count.

I think that "perfectionist" is not a strong enough description of this character, since it's the one word in your logline that separates your story from a thousand other "I killed the wrong man, now must uncover what's really going on" type stories. This guy is meticulous - I imagine almost obsessive compulsive. I could be wrong, but I would suggest you having a bit of a think for a more precise (and extreme) description of his character flaw.

Other than that it's working really well.

I like it. You established the character's need (perfectionist who screws up) and a ticking clock with the mob.

Based the logline, I see the action of the story as being, "to find out." It sounds cerebral. It works as a mystery, but I'm wondering if you can add more. Make it more visceral. I don't know, maybe have the mob chasing him right from the start?