Jack Abbott and Phyllis Summers, following Phyllis waking from a year-long coma, made plans to go to St. Barts to get married. Although a sudden storm interrupted their wedding on the beach, they were married in their hotel room. But afterward, Jack was kidnapped courtesy of of his nemesis Victor Newman, and a man with Jack's face named Marco Annicelli took his place impersonating Jack.

Jack was being held hostage in a hut on St. Barts. Jack woke up one morning next to the murdered body of his captor and found blood on his hands. Victor's paid cop found her body and also reported to Victor that Jack was missing. Victor told him to let everyone believe that his captor had been dead for months, and to find Jack.

Jack stowed away on a smuggler ship, and found cocaine in the cargo but was caught. Jack told them who he was, a Genoa City, Wisconsin, cosmetics company CEO. He offered a payoff to return him back home, but Captain Churchwell knew him as Marco the drug lord who had stolen his money. The captain told Jack that a lot of people wanted Marco dead, and he could make more money by ransoming him to them, after which he pistol-whipped Jack. Marco's old girlfriend, Marisa Sierras, showed up and began kissing Jack, thinking he was Marco. Marisa managed to get the key to Jack's handcuffs, and he told her about Genoa City, and that all the stolen money was hidden there. But Jack's hopes for freedom were dashed when the captain caught them kissing and put Marisa in chains as well.

Jack was able to convince Marisa that he was not Marco. Marisa seduced Captain Churchwell while Jack started a fire in the hold. When the captain came to investigate, Jack knocked him out, and the ship blew up. Jack and Marisa were the only survivors, winding up on an island where they found an abandoned hut. Jack's leg was hurt badly, his wounds so infected that he passed out with fever. Marisa left him there to go find help. Marisa returned with a phone and some meds. She called Kyle but Marco answered the phone. Marisa lied to Marco that Jack was dead, and begged Marco to wire her money to keep her safe.

Jack realized that Marco had taken over his life. Marisa called Marco a son of a bitch. When no money was wired, they realized that Marco knew she had lied. A big bruiser walked in the door with a gun and orders from Marco to kill them. Jack imitated Marco to intimidate the guy, got his gun away, and made him get them off the island. Jack arrived home, and walking into an empty house, felt grateful to be home. When Phyllis walked in, he hugged her. Jack was about to tell Phyllis about Marco when Summer walked in and chided him for setting up Victor. Getting a text from Marisa, Jack left. Marisa had found out that Jack's company Jabot had been merged to become Newman-Abbott and that Marco and Victor were meeting in the park for some sort of showdown. Jack left to join them, and Marisa called the police. Victor and Jack argued, and when Jack reached into his suitcoat, Victor shot him. Jack's friend Gabriel Bingham persuaded Victor to give him Newman-Abbott in exchange for covering it up for him. When Marco arrived, both of them were shocked to realize it was the real Jack on the ground covered in blood, but still alive. Marco left just before the police arrived, and Gabriel told the police he had found Jack, but had not seen the shooter. Jack was taken to the hospital, had surgery, and ended up in a coma.

Marisa let Marco into her hotel room, thinking he was Jack. They fought, he kissed her, she bit him, and said that she hated him. Marco booked a jet to take them to the Caribbean, but Marisa pulled a gun on him, telling him that she was turning him for what he had done to Jack. Marco dared her to shoot him, but because she still loved him, she could not. Marisa wanted to stay in the U.S. and have a better life. But Marco told her that Jack and Victor were people who would stab you in back, to go with him where she belonged. He sweet-talked her into flying away with him, but on the way, Marisa realized he was taking her somewhere else to kill her. She grabbed the steering wheel, the car veered off the road and into a lake. Marco did not surface and was assumed drowned by Marisa, who staggered into The Underground bar wet and shaken. Noah Newman was closing up when Marisa staggered into The Underground wet and shaken. She told Noah that she and her boyfriend had had a fight, and she had nowhere to go. Noah gave her a blanket and coffee, and let her spend the night on the office couch. The next morning Noah hired her to work at the Underground and got her a room at the athletic club. Marisa couldn't believe that someone could be so kind to a stranger like her.

Jack had told Marisa about his friend Gabriel, a young man who was actually Victor Newman's presumed dead son, Adam. But Adam had gotten plastic surgery and was posing as Gabriel Bingham as part of a plot to get revenge on his father and resume his life with his wife Chelsea and son Connor. Marisa called Gabriel telling him that she could be his greatest ally or worst enemy. Adam asked if they could meet, Marisa answered, "Eventually." Later that day, Noah introduced his new employee Marisa to Chelsea. Marisa knew her designs and was impressed to meet THE Chelsea Lawson, and met "Gabriel" who was with her.

Noah told Marisa about the murders of his brother-in-law Austin and his bride Courtney, and DNA found being traced by police to drug lord Marco Annicelli. But when the FBI got involved the DNA suddenly matched Tobias Gray, who since died, instead. Marisa told Noah she did not know Marco, but that her boyfriend had traveled in the same circles, but that he was gone and could not help. Phyllis caught Marisa talking to Jack in his hospital room. Noah intervened and identified Marisa. Jack would not answer if he knew Marisa. Noah asked Marisa what she was doing in Jack's room, asking if it had anything to do with Marco. Marisa told Noah to forget Marco, but later admitted that he was her former boyfriend, but was assumed dead in his car at the bottom of Lake Delaney. Mariah and Kevin decided to check, but found the car with no one inside.

When questioned by Victor, Marisa said she was raised by her aunt, but when the house became too crowded, Marisa was sent to an orphanage. Having been orphaned himself, Victor could identify with her plight. Marisa told Victor he had shot the real Jack. Victor tried to pay her to leave town. After Kevin exposed Marisa's connection to Marco, the police questioned her and got a composite sketch of Marco.

Noah was falling for Marisa, but felt disloyal to Courtney. Eventually they did make love, but then the police told Noah that the sketch was of the dead captain of a ship Marisa had been on in Peru when it blew up, not of Marco. Noah confronted Marisa for trying to protect Marco, but she said she had done it to protect herself from Marco.

Jack enlisted Marisa's help in luring Marco to the Abbott cabin. Marisa sweet-talked Marco, and he ended up tied to the bed. Jack arrived and he and Marco exchanged heated threats, as did Phyllis with Marco, but neither could kill him like they wanted to. Marco seethed at them, calling them cowards. Jack was ready to go to the police to get justice against Victor and Marco, but Phyllis talked him out of it. Victor arrived, and talked them into letting him return Marco to prison in Peru, as they all had too much to lose if the truth ever got out. On the way there, Victor had one of his men cut off Marco's ear so he could never be mistaken for Jack again. Victor tried to send Marisa back too, but Jack intervened, and she was allowed to stay, but warned by Victor to shut her mouth about the entire incident or else. Victor offered Marisa half million to leave town, but she refused. Later Noah asked Marisa to find an apartment and move in together. She hedged. Just in time, a Newman check for half million dollars was delivered. Marisa explained that Victor had tried to get rid of her, and just as Victor had planned, Noah assumed that she had taken the bribe.

Marisa was shocked when a young handsome man named Luca Santori showed up at The Underground looking for his wife. She covered with Noah that his wife was a friend of hers, as she handed Luca the wife's phone number, which was really a note to meet her in the park. After Luca left, Marisa told Noah that as soon as her friend had married him, he became possessive and jealous, the wife had become afraid and left. Marisa met Luca, and he reminded her that she had never divorced him after Marco took her away from him. He told her that Marco was in prison, and had told him where to find her as payback for her part in putting him there. When Victor found out, he was concerned that Luca was part of the notorious Santori family in Spain, and he pressured Marisa to get rid of him by seduction if necessary. Noah eventually guessed that Marisa was the runaway wife of Luca, and broke up with her over her constant lying. Marisa said that she had married Luca as a way out, and Luca had only married her to oppose his family. Maria pleaded with Luca to give up, give her divorce. He agreed, but as Marisa was leaving town, she got mugged, and was hospitalized. Noah was called from information found in her phone, and they embraced. As a sign of her complete honesty with Noah, Marisa told him of the plot by his grandfather Victor to replace Jack with Marco, how she had helped Jack get back to Genoa City, and helped to get Marco captured and sent to prison. Noah was disbelieving, but confronted Jack and Victor with his knowledge of the plot. Victor made excuses, but admitted it was true.

After her release from the hospital Marisa admitted to Noah that she had been pregnant when she left Luca, and had given up her daughter for adoption. Luca claimed to have found their daughter, whom Marco had sold, and together they could claim their little girl who had been named Ava. Marisa agreed to live with Luca for a month to reclaim her. Noah told Marisa she could not trust Luca, and Noah would help her find daughter instead. But when Noah asked Victor for help, Victor refused unless Noah broke things off with Marisa. Noah refused, but when she found out that he could not help her, Marisa returned to Luca.

The annual Delia Halloween costume party benefit was held at Top of the Tower, with Noah dressed as Charlie Chaplin. Marisa, dressed as a Spanish folk doll, was there with Luca, dressed as a Spanish conquistador. Luca did his best to goad Noah, even when a fire broke out on the floors below, he bragged how he would save his beloved Marisa, as he put her onboard the rescue helicopter and stayed behind with Noah. They were both rescued on a later flight.

Luca made a deal with Victor Newman for the Santori family to help finance the rebuilding of Newman Enterprises, then prepared to return to Spain, having given up on winning Marisa back. Marisa begged, what about Ava. Luca took her to Spain with him, and Marisa overheard Luca discuss his private detective that Ava played in the park each day. She went to the park to see Ava, and Luca caught her trying to steal the child. But Marisa returned to Genoa City without Ava, explaining that after they had spoken with Ava's adoptive mother they agreed it was the best place for her, and had set up a trust fund. Noah did not believe Luca was being sincere with Marisa, and contacted the FBI trying to keep Luca out of country. Victor tried to pay back the Santori family, claiming the contract had included a three day right of rescission. But Luca would not accept, demanding an office for himself and for Marisa, his assistant. They were surprised when they were shown to the offices by Noah, who had gone back to work at Newman to learn from his grandfather. On Christmas eve, Marisa welcomed Luca to her room, and they made love.

The Santoris wanted Newman to expand into the American mining business. Agreeing that their fathers were very much alike and they hated them, Adam proposed a plan to Luca to force their fathers out and take over their respective family companies. Marisa told Luca not to trust Adam. Luca told her that he hated his father ever since he had broken them up. Luca agreed to expose his father's illegal dealings, and Adam would simultaneously expose the Marco fiasco. Luca asked for time to get the proof to guarantee that his father would go down. Marisa became that proof when she told him that the Santoris were Marco's only backer. Luca told Adam they needed to find Marco to seal the deal. Adam spoke to Victor and handed Luca what Victor had given him.

Marisa left the New Years Eve party chasing after Noah, too late, she watched him leave the parking garage. Behind where his car had been parked, she found Billy Abbott unconscious and called an ambulance. After discovering that Billy had been beaten, then run over by a car, Paul asked Marisa what she had seen, and she said she saw nothing. Marisa told Noah, and Noah was shocked that he must have backed over Billy. Noah wanted to confess, but Maria and later Victor talked him out of it, and Marisa had Noah's tires secretly changed and disposed of.

Luca and Marisa became lovers again. Adam was kidnapped, Victor assumed by the Santoris. So Victor had his men nab Marisa, telling Luca he was going to swap Marisa for Adam. Victor had her set free when it turned out that she was not "the girl" Adam's captors wanted. The exchange was made with Natalie, the right girl, and Adam was returned.

Luca informed Marisa of the setup Adam and Victor had pulled on him to oust them from Newman, but that he had outwitted them by using the threat of exposure of Noah's hit and run to stop them. Noah went to Luca ready to join him to bring down Victor. But Adam convinced Noah to flee the country, and Marisa went with him. Word reached Victor that Noah had betrayed him, so Victor went to the police and told them that Noah had been Billy's hit and run driver, and that Marisa had taken him out of the country and covered it up. Noah woke up in Genoa City Memorial chained to the bed with broken ribs and internal bleeding after running from his arrest for hit and run. Marissa tried but failed to convince police chief Paul that she had been driving the car. Paul accused Victor of covering up for his grandson, then changing his mind. Leslie Michaelson became Noah's lawyer, and Noah ended up sentenced to 12 month's probation and 60 hours of community service. Noah celebrated by giving Marisa an engagement ring, even though she was still married to Luca. But Luca suddenly agreed to the divorce, hoping to marry into the Newman family with Summer.

Victor went on trial for kidnapping Jack and replacing him with Marco for months, and was convicted to 10 years in prison, in part by Marisa's testimony to what she had seen with Jack, and what Marco had told her later.

In February 2017, Noah told his friends that he and Marisa had broken up, and that she had moved to Spain now that she was being allowed to visit her daughter Ava.