Hit-Girl is the superhero identity of Mindy McCready who's a young but effective assassin. Her father is famous NYPD officer Damon who was framed for drug dealing by mob crime lord Frank D'Amico after rejecting his offer to work for him. He was five years imprisoned before she was born and her grief-stricken mother was pregnant of Mindy at the time before she committed suicide. The doctors managed to save Mindy on time before her mother died. She was adopted by her father's former partner sergeant Marcus Williams. Damon was given custody of Mindy after his release from prison.

She was trained by her father in martial arts from an early age, with the purpose to become an costumed superhero and assassin. He taught her how to use various forms of weaponry, including guns, knives, spears, grenades and how to wear a bulletproof vest. The deadly father/daughter crime-fighting duo Big Daddy and Hit-Girl take revenge for the death of her mother and Damon's imprisonment by tracking down and killing the henchmen and drug dealers of crime lord Frank, one by one until they reach himself.

She's impressed by the courage of an vigilante named Kick-Ass, who gains extensive media attention. She encounters Kick-Ass for the first time when she saves him out the hands of petty drug dealer named Rasul and his thugs. She and Big Daddy visit him at home after tracing his IP address, when they discover his true identity as Dave Lizewski. They see potential in him as crime-fighter and stay in contact with him, if he ever need their assistance.

The latest superhero Red Mist (the son of Frank D'Amico in reality) uses Kick-Ass to arrange an meeting with Big Daddy and Hit-Girl at one of their safe houses. She was viciously gunned down by an traitor and falls out the window of the safehouse during the appointment. Big Daddy and Kick-Ass are taken captive by Frank D'Amico's men. She survived the attack due the wearing of a bulletproof vest and tries to rescue them. Her father and Kick-Ass are bound to chairs and brutally beaten on national television and later on internet. She manages to rescue them and defeats all goons, but she can not prevent that one goon is putting her father on fire.

An heartbroken Mindy and a fatally burned Damon express their love for one another before he succumbs to his burns. She then frees Kick-Ass and the two escape in the Mist Mobile. She's initially angry on Kick-Ass for his unwilling role in her father's death. She has decided to finish what she and her father started in order to bring down Frank D'Amico's organization. She wants that Kick-Ass is helping her by giving him the choice, to either live with the guilt of inadvertently causing the death of her father, or redeem himself by helping her defeat Frank D'Amico. He joins forces with Hit-Girl, who gives him instructions on how to use a jet pack.

She gains access to Frank's headquarters by disguising herself as lost school girl. She promptly kills the guards and returns to her Hit-Girl guise. She and Kick-Ass then confront Red Mist and Frank D'Amico himself and she faces the man who's responsible for the death of her parent's in his office. She manages to kill Frank and his men after an intense martial arts duel with result that her parents are finally avenged. 

Skills and Abilities

• Weapons Expert: She is trained in hand-to-hand combat and in fighting with blunt and bladed weapons. She has been taught about guns, inventors of guns and even action movies and action movie stars.
• Martial Arts and Combatant: The nature of her training has made her particularly brutal and remorseless in combat.  Her physical and skill set are virtually unmatched in comparison with other characters. She's individually the most powerful character of the super heros. She is limber and hard to catch because of her small size.
• Multilingual: She can also speak Russian next to English.
• Weapons: She carries a selection of small throwing blades and a throwing blade attached to a wire. She is also very skillful in the use of a flamethrower and also uses a pair of Glock 23 pistols to slaughter mobsters en masse.