Clay meets her while scouting but refuses to be her agent as she is a dead ringer for his late wife, Sara. Clay accidentally slips up and calls her "Sara" while refusing to represent her and Katie does research on Sara and decides to take advantage of the situation by dying her hair blonde to match Sara and stealing their wedding video and a diary in order to learn various aspect of their married life. Katie shows up at the opening of Quinn's photo gallery "Focus" and purchases a photograph of Clay (which she later breaks inside of the store when she breaks in). Quinn learns from Clay that Katie has been pretending to be his wife and warns her not to do anything as Katie is mentally unstable and has to take lithium. Clay finds Katie hanging off of a bridge that he and Sara jumped off of during her college days and plays enough with her fantasy of being Sara so that she can be arrested by the police. In the closing moments of the season finale, Quinn and Clay are both shot by Katie in the bedroom of Clay's beach house, and she sneaks off into the night, leaving them for dead.
Quinn and Clay both end up surviving the murder attempt miraculously since their bodies were discovered 12 hours after the shooting. Quinn takes a trip to Africa and while there, she stays an extra week, managing to track down Katie and take photographs of her, planning her own revenge. Katie, however, became aware of Quinn's presence and returned to Tree Hill on the eve of a hurricane to finish what she had started. She returns and attacks Quinn in the beach house and while belittling Quinn about how she will never be going away, Quinn runs and tackles her over the balcony, sending them into the pool below. Katie sees Quinn's motionless body entangled in the pool cover and heads inside to pour herself a drink while listening to Clay and Sara's favorite song. Quinn, however, is still alive and runs up to the upstairs bedroom to retrieve Katie's gun. As Katie arrogantly tells Quinn the gun is empty, Quinn continues to pull the trigger until she finds the chamber with the bullet inside. Katie is shot in the chest and collapses to the floor, gasping for air. Quinn calls an ambulance, refusing to let Katie suffer the same way she did with Quinn and Clay.