Mackenzie appeared in Genoa city in 1999. She had run away from her mother and alcoholic stepfather in St.Louis and come to Genoa City in search of her father and grandmother. Upon finding them, she met the stubborn and deceicive Jill Abbott, who she would be living with.
      Mack entered the teen scene to be immediately accepted by the "in crowd", which consisted of Jill's son, Billy - who mack got along with about as well as she did with Jill (not well), and Billy's snobby girlfriend,

Brittany. Then there was Billy's best friend, Raul, who was immediately love struck by the lovely Mackenzie. Along with them was J.T, another friend, and his girlfriend, Rianna.
      In Mack's first months in Genoa City, she celebrated her 16th birthday with a huge party at "Crimson Lights" - the town's local hang-out. Unfortunately, the happy night did a complete 180 when a few of the teens (Mack not included) decided to skip the b-day party and go to a keg party. Billy fell drunk in the snow and, after being left for several moments unconscious, was struck with hypothermia, and barely made it.
       Soon to come was the high school prom. Billy was crowned Prom King and, surprisingly, Mackenzie was crowned Queen. The expected Queen, Brittany, was left in the cold, as her boyfriend and rival stood shining from the stage. That was the night Mack and Billy finally admitted their long-hidden feelings for eachother.
       Ever since, their love for eachother has kept them together, while they've had to hide their relationship from Mack's boyfriend, Raul, and Billy's girlfriend, Brittany. But most importantly, Billy's mother, Jill, who would do anything in her power to keep them apart. No one knows abou them except for Billy's half-brother, Jack and half-sister, Ashley.
      Mack is spending the summer of 2000 working behind the scenes of the "Glow by Jabot" website promotion.