Decker Moss was a tough-talking con artist who rode into Port Charles in 1989 to become a bartender. Decker also had ties to Port Charles as his half-brother Colton Shore had resided in town for a few years and his cousin Lucy Coe lived there also. One night, however, Decker accidentally hit Felicia Jones with his motorcycle! Felicia then suffered from amnesia and Decker told the beautiful woman that she was his girlfriend and named her Phoebe. Decker didn't know that the woman he was conning was in fact the current fiancée of his half-brother Colton Shore! Felicia eventually learned the truth and left Port Charles.

Decker was still acting as bartender when he met the young, beautiful Dawn Winthrop, a student nurse at General Hospital. Decker was drawn to Dawn but she was engaged to be married to the wealthy Ned Ashton. Ned's mother Tracy Quartermaine hated Dawn and vowed to break the couple up. Decker joined forces with Tracy in order to get Dawn for himself. Things got easier for Decker and Tracy when the trashy money-hungry Wendy Masters came to town. Wendy Masters was an ex-employee of the Green Meadows Health Spa who worked there at the same time that Ned Ashton was a tennis instructor there under the name of Ward. Wendy also knew that 'Ward' had an affair with Monica Quartermaine unknowing that she was his aunt! Wendy planned to blackmail Ned and leave town but before the secret was revealed, Wendy was found dead on a pier merry-go-round! As an investigation was done into Wendy Masters' murder, the secret was revealed and Dawn discovered her mother's and her fiancé's affair! Dawn was hurt and left town with Decker but the police were after them! Evidence at the scene pointed at Decker as Wendy's killer! Decker however was innocent and eventually cleared when an old carnival worker named Drago confessed.

In 1991, Decker and Dawn returned to Port Charles so that Dawn could make amends with her mother and continue her nursing at General Hospital. Decker proposed to Dawn, then left for a few months to solve a gambling problem. He returned and they were very happy. Unbeknownst to him, his new business partner, Edge, planned to break up Decker and Dawn to obtain Dawn's wealth. Decker and he bought Colton's health club, Body Heat, turning it into a video bootlegging operation. Decker told Dawn it was an advertising agency.

Old enemies of Edge's set the club ablaze with Decker, Edge, and Dawn tied up inside. Dawn was devastated when she learned Decker lied to her. Edge managed to free himself, bludgeon Dawn and Decker with a pipe, and put the pipe in Decker's hand. Dawn died. Decker was arrested for her death. Decker pleaded his case saying that he truly loved Dawn and would never do anything to harm her. He was then cleared of the murder when Frisco Jones found a videotape showing Edge Jerome killing Dawn. Decker left town shortly there after and never returned.