Scott Carlin is a 24-year-old high school dropout, who lives with his mother Margie and his sister Claire on Staten Island. Scott's firefighter father Stan died fighting a hotel fire when he was young, a loss that continues to affect him; he also deals with numerous medical problems, including Crohn's disease and ADHD, and smokes marijuana constantly. He is unemployed and spends his days hanging out with his friends, including Kelsey, who he is sleeping with. Kelsey wants the relationship to be more serious, but Scott fears commitment and worries he is not good enough for her. Claire, who is leaving for college, expresses concern that Scott's neuroses will grow out of control without her there.Scott dreams of being a tattoo artist and practices regularly on his friends, although his work is extremely inconsistent. One day, while hanging out with his friends on the beach, he is approached by a 9-year-old boy, Harold. He asks Scott to give him a tattoo, but runs off after Scott draws a single line. Later, the boy's father Ray shows up at Scott's house. He is initially furious, but is attracted to Margie and eventually asks her on a date. Margie, who has not dated since Stan's death, agrees. As things become more serious, Margie reveals their relationship to Scott, who is disturbed that Ray, like Stan, is a firefighter. Ray takes Scott to a Staten Island Yankees game with his co-workers, but finds it difficult to talk to Scott, who argues that firefighters should not have families because of the pain that is caused by their deaths. Margie and Ray tell Scott that they expect him to move out of the house, which upsets him. While visiting Claire, Scott reveals he plans to break up Margie and Ray, claiming that the relationship is unhealthy. He gets a job as a busboy and begins walking Harold and his sister Kelly to school each day, and grows close with them. Meanwhile, Scott's friends plan to rob a pharmacy for oxycodone pills to sell. Scott is uncomfortable with the plan but agrees to be the lookout. The robbery goes awry when they are confronted by the pharmacist and his wife. Scott's friend Oscar is shot and they are all arrested, but Scott manages to escape.Scott meets with Ray's ex-wife Gina, who tells him several negative things about Ray, painting him as a homeless gambling addict. Scott relays this information to Margie in an effort to break them up, only to end up in a physical confrontation with Ray when he discovers what has happened. A furious Margie kicks both men out of her house. With his friends in jail, Scott struggles to find a place to stay. He sleeps with Kelsey in the hopes that she will let him stay with her, but she is disgusted when she realizes his ulterior motives and refuses. Out of options, Scott goes to Ray's firehouse, and is allowed to stay there in return for doing odd jobs. He gradually bonds with Ray and the other firefighters, who tell him stories about his father, humanizing him and helping Scott to accept his death. Ray learns from Harold that Scott is a talented artist, and agrees to let Scott tattoo his back as practice.One day, a man shows up at the firehouse with an abdominal wound while Scott is there alone. Scott brings him to the hospital, where Ray arrives, using his firefighter connections to get the man the help he needs. Margie, who works as an emergency room nurse, sees Scott and Ray and reconciles with them both. Ray shows Margie his tattoos; a number of them are offensive or violate Ray's criteria, but the most prominent is a drawing of Margie, Ray, Scott, and Claire together. Scott surprises Kelsey at the Staten Island Ferry, where she is heading into Manhattan to take a civil service exam. He rides on the ferry with her, where he confesses his love for her, and the two kiss. Kelsey heads into the exam, leaving Scott alone with his thoughts in Manhattan.