Summer arrived in Port Charles as a mystery woman spotted by a grieving Luke in the park. Luke saw a close resemblance between his beloved Laura, who had just been put away in a mental institution, and the mystery woman. When he pushed the mystery woman out of the way of an oncoming car, the driver of the car said he never saw a woman, making Luke's therapist believe that Luke was just making up the mystery woman.
After Summer told Luke that she was a call girl and revealed that her real name was Laura, Luke said that he would pay her to simply spend time with him and play games of make-believe, which involved re-enacting special moments between Luke and his wife, whom Summer believed to be dead. Summer reluctantly agreed to the arrangement. A series of encounters between Summer and Luke followed, none of which could be proven by Luke afterwards. One of the moments involved breaking into Wyndham's Department Store and recreating the famous scenes of Luke and Laura dancing together there. However, these encounters didn't help Luke ease the pain over losing Laura to mental illness.
During their encounters, Luke got Summer to admit that she was hiding from a powerful client who wouldn't let go of her. Luke offered to help, but she said no, that she wished to stay in hiding. Summer even tried to convince Luke that she was not real so that he would stop trying to see her. But Luke was finally able to coax Summer out of hiding when he sat on the ledge of the roof of General Hospital. Cameron was in the process of trying to talk him down when Summer revealed herself, dispelling any doubts about her actual existence.
Summer met Lucky when she was enrolling in some college courses. But she introduced herself as Laura, so Lucky never made the connection between his dad's mystery woman and the new beautiful blonde he couldn't get out of his head. They met on various occasions, and a friendship grew between them. Summer was torn between her growing feelings for Lucky and her encounters with Luke; although she also didn't realize that the two men were related.
When Summer's powerful former client, a senator, beat her and had her arrested, Lucky blackmailed Scott into helping Summer dispose of the senator. Summer was grateful for Scott's help until she realized that he wanted to date her in return. She refused. After the incident, Lucky and Summer's friendship blossomed into something more, although it took her awhile to get used to being with a guy who didn't pay her.
Summer nearly figured out that she had been seeing both father and son, but it was Lucky who ended up seeing Luke and Summer together. Lucky got upset and believed that she'd been playing them both for suckers, hoping to gain financially from them. But they decided to keep Luke in the dark about his knowing Summer. When Scott discovered the truth, he gleefully told a shocked Luke. Luke tried to get Lucky and Summer back together. But they still had problems, and Summer returned to being a call girl.
Nikolas tried to keep Lucky and Summer apart by bringing up Summer's call girl status. He warned Summer to stay away from Lucky or their deal was off and she'd never find her brother. Summer told Luke about her missing brother, infuriating Nikolas. Eventually Lucky discovered that Nikolas had hired Summer to distract Luke from trying to find where Laura was being institutionalized. Lucky told Luke and confronted Nikolas. Summer tried to get Luke to intervene because she didn't want to be the cause of Lucky getting hurt. Summer told Luke that Nik had hired her to dress like Laura to get Luke's attention and then to make him fall in love with her. In return Nik would pay Summer cash and tell her where to find her missing brother. Summer had met Lucky by accident; so when she developed feelings for Lucky it made her job with Luke difficult to finish. Luke agreed to forgive her but told her never to scam him again or he would kill her.
Lucky promised to help Summer find her brother, so they searched Wyndemere and found some clues that could lead them to Matt. Together with Luke, they headed off to Greece. Along the way, they found a valuable antique coin identical to one at Wyndemere. They also found Matt but an unknown assailant stabbed him in the back before he could reveal more than the fact that Summer was not his sister. Summer confirmed that she was only looking for Matt so that he would tell her where the money was hidden. They got arrested for Matt's murder and Nik showed up to bail them out, although Luke refused to leave with them.
Summer stole the plans to a Cassadine estate in Russia and took off. She discovered that the estate was now a bordello, but she met up with Luke while there. Lucky and Nik weren't far behind, so Luke and Summer took off again. Lucky and Nik tracked them down to some tunnels on the estate where they were searching for the fortune. Luke beat them all to it, but they discovered that the real money had been replaced by worthless coins.
Back in Port Charles, Summer finally admitted that she loved Lucky. She became a waitress at Kelly's so that she could move into the room across from his. She also asked Luke to stop the fight with Nik because Lucky was caught in the middle. Luke refused.
Summer accompanied Lucky to see Laura at the mental institution. Summer got caught in the middle of a physical altercation between Luke and Lucky when Luke discovered that Lucky and Nik had hidden Laura again. Summer ended up knocking Luke out to get him to let go of Lucky. Later a drunk and doped up Luke returned to Lucky's place and mistook Summer for Laura. Luke talked to "Laura" lovingly, and Summer went along with it, feeling sorry for him. Luke pulled a knife and promised to protect "Laura," but when Lucky arrived, Luke left. Later Summer helped Lucky trick Luke into being committed to a mental hospital.
At Nikolas and Emily's engagement party at Wyndemere, Summer was walking out on the bluffs in the heavy fog when she was pushed from behind. Nik and Lucky rushed to the bottom to discover that the fall had killed her. Lucky was devastated and vowed to find the person responsible.
Lydia overhead Stefan getting rid of his hired assassin for pushing the wrong woman over the cliff. Stefan tried to cover up his involvement by blaming Luke, who had also been on the island that evening as an unwelcome trespasser. Lucky attacked a shocked Luke and accused him of being responsible for Summer's death. Alexis theorized that Luke didn't do it, and that Emily was the intended victim, since she had also been out there that evening. However, no one else seemed to believe that Luke was not the one who killed Summer. Lucky later learned that one of the servants on the island that night had since disappeared, and he believed that servant was the one who had pushed Summer off the cliff.
When Lucky grew frustrated over how Mac was handling Summer's murder case, Mac challenged him to become a cop to be able to investigate her murder himself. So Lucky did just that. He also teamed up with Lydia to gather evidence against Stefan. Lydia managed to secretly tape Stefan discussing the fact that he had hired an assassin to kill Emily but the guy had pushed Summer by mistake. The tape was enough to get Stefan arrested, but Alexis worked her lawyer magic and got him released. Luke had returned to town by this time and vowed to exact his own kind of revenge on Stefan for Summer's death. Luke kidnapped Stefan and summoned to a warehouse all the parties involved in the night of Summer's death, where he held a mock trial against Stefan. Luke also broadcast his trial on TV for all of Port Charles to see. After much badgering by Luke, Stefan broke down and confessed his wrongdoing, claiming it to be out of love for Nikolas. Luke finally got his revenge when he located and stabbed the fugitive Stefan, who had been hiding out in the tunnels at Wyndemere. Stefan then fell off the same cliff that Summer had, and he died.