be out for/after (one's) scalp

To seek vengeance in an especially hostile or belligerent manner. This phrase is often used hyperbolically, although it can refer to physical violence. I'd avoid the boss if I were you—he's thinks that blunder was your fault, so he's out for your scalp. I got robbed by some punk last night, and now my brother is after the kid's scalp. She's the one who lied and destroyed my reputation? Oh, I am out for her scalp now!