Susan Moore arrived to Port Charles in 1978, and she began flirting with District Attorney Mitch Williams, who was being pursued by Tracy Quartermaine. Tracy stopped at nothing to have Mitch all to herself. What both women didn't know was that Mitch had ties to the mob. Mitch married Tracy for her money, but that didn't stop him from cheating on her with Susan. Mitch was using Tracy's money to fund his campaign for State Senate. Mitch found the money Tracy had more valuable than the love he had for Susan, and he left Port Charles for Albany with Tracy.

When Alan discovered that A.J. was actually his son, he announced it to the public and Rick left Monica. When Rick left Monica, she moved back into the Quartermaine Mansion and rejected Alan's love. It wasn't long before Alan began having an affair with Susan. Alan refused to divorce Monica because he didn't want to lose custody of little A.J. Susan became pregnant with Alan's child, and she gave birth to son Jason. After hearing of this, Monica filed for divorce and sued for full custody of A.J. Alan went back to Susan, and he became impotent. Apparently, his being apart from Monica induced his impotency. So, Alan moved back into the Quartermaine Mansion, but Monica proceeded to stay away from him. However, Monica was desperate to receive full custody of A.J. Monica went as far as to getting pictures of Alan and Susan together. Alan truly did want to reunite with Monica, but she refused to do so until he cut Susan out of his life. Alan dumped Susan, and reunited with Monica.

However, Susan wasn't going to allow Alan & Monica's reconciliation to be a lovely walk through the park. Since she was the mother of Alan's illegitimate child, Susan sued him for millions and millions of dollars. The court rewarded Jason with a million dollars, but Susan was only allowed ten percent of it. Infuriated, Susan began drinking and Alan decided to sue her for sole custody of Jason. However, Monica didn't want Jason to live with them. Meanwhile, Susan married Scott Baldwin, but she didn't know that he only married her to get at Jason's trust fund. Susan eventually met Lila's REAL husband Crane Tolliver. Apparently, Crane and Lila's divorce was never finalized, and this factor made Lila's marriage to Edward invalid, and Alan and Tracy illegitimate children. Susan and Crane became money-hungry, and decided to use this piece of information to their advantage.

After Susan and Crane divulged the information onto the Quartermaine clan, they went on to blackmail them with it. Under Crane's instructions, Susan demanded $2 million for Crane & Lila's unsigned divorce papers. Around the same time, Susan discovered that Scott was trying to steal money from the trust that was set up for Jason. Susan planned to have Scotty prosecuted for forgery. On the night that Susan planned to make the exchange with the Quartermaines, someone arrived to her cottage and killed her! Edward, Alan, Monica, and Jackie Templeton all arrived at Susan's cottage together to find Susan lying on the floor dead. The entire family was a suspect in her murder. However, it was later revealed that Crane killed his accomplice when she attempted to back out of their deal.

Private investigator Robert Scorpio shot and killed Crane soon afterward. However, Crane managed to give Edward's illegitimate son Jimmy Lee Holt the unsigned divorce papers before he died. Lila and Edward went on to make their marriage legal, and Monica grew to love Jason as though he were her own flesh and blood. Jimmy tried to blackmail his own family for money using the documents, but the documents were ultimately destroyed in a fire.

Several years after Susan's death, Heather revealed that Susan had given birth to fraternal twin sons. During Susan's labor, she gave birth to one child and then lost consciousness. Before she regained consciousness, she gave birth to another son which Heather gave away to the delivery nurse. In exchange, the nurse took care of the medical bills associated with the birth. The son Susan never knew about was named Robert "Franco" Frank. Franco viewed a home video in which he saw a name other than his mother's on his hospital identification bracelet and learned that he was adopted.