She was hired by Victor Donovan to keep an eye on, and eventually kill Helena; Christie's mission was to stop her from winning the third Dead or Alive Tournament, and in the process prevent her from discovering more about Donovan's secret plans and his anti-Douglas faction.
Disguised as a servant to Helena, Christie also intercepts Bayman, who is in the process of seeking revenge on Donovan for trying to have him killed. Christie fights him despite what he thinks of her; as "one of Donovan's lap dogs". She later confronts Helena, where she reveals her real occupation as an assassin sent by Donovan. While Helena defeats Christie, she is unable to win the tournament. After the tournament, Christie then returns to her apartment, where she receives yet another mission.
Costume Easter Eggs: Pressing X when selecting C2 OR C3 gives an alternative colour scheme.