เสียดาย

We are introduced to the four main characters Pu, Ngoh, Duean, and Pam and their different family backgrounds. Pu lives in Kanchanaburi and wants to move to Bangkok to live with her mother while Ngoh's family just moved to a different part of Bangkok to open a new shop. Duean and Pam live in the poorer neighborhoods within Bangkok where Duean's father works as a construction manager and is looking to buy a new house. Pam's father is a police officer and her mother has a gambling problem.

Duean visits her father at the hospital while Pu moves to Bangkok to live with her mother and her new husband. Ngoh's father is wary of his wife as she seems a bit too friendly with the customers. Duean's father's condition worsens and Pam's mother continues to gamble.

Things get heated with Pu's family as her mother starts to show signs of favoritism towards her younger children and Duean's mother receives bad news. Pu and Ngoh meet for the first time at school and Pu meets Joe and Pam at the mall.

Pu starts smoking and becomes friends with Ngoh. Duean comes up with a way to help support her family and help pay for her father's medical bills. At Pam's house, her father chastises her mother for her gambling problem while Ngoh's father lashes out at her mother. Pu grows more and more distant with her family and develops a little crush.

Duean's mother searches for a job to pay off her husband's hospital bills while Ngoh and Pu become closer. Ngoh and Pu meet up with Duean and Pam at the mall where they meet a waiter, Frank, who has taken a liking to Ngoh. Pu and Pam also meet Yok for the first time and Pu goes on a trip with Louis. Ngoh's father becomes more wary of his wife and uses alcohol to cope. He starts to get aggressive with her and Ngoh attempts to intervene. Pu's mother chastises her for going out late, making her feel more and more distant.

Ngoh struggles to cope with her aggressive alcoholic father while Pu continues to smoke more and more. At school, Pu and Ngoh prepare for their performance while Ngoh's senior admirer attempts to win her over, leading to a jealous freshman confronting Ngoh. Duean confides in Pam as she desperately wants to help her mother out. Pu introduces Louis to Ngoh and goes on a trip with him and Louis's backstory is introduced. Duean's mother continues to struggle to pay for her husband's hospital bills along with her other loans.

Duean's mother finds a job as a dishwasher at a nightclub where she is faced with a difficult decision. Ngoh's father attempts to reconcile with his family by taking their family out for dinner. Duean applies for a job at a local café to help her mother with Pam joining her. Pu feels like an outcast in her own home, with her mother always favoring Lookmoo and Pom. The senior who likes Ngoh is persistant and steals her and Pu's bags and Pu gets annoyed. Pu gets caught smoking at school while Ngoh voluntarily takes the blame.

Ngoh and Pu are punished by their parents for smoking and have a parent-teacher conference at school. Pu goes on a trip with Louis after the conference. Pam starts to get tired of her job at the café and Ngoh starts taking more pills to help her sleep better. Pu and Ngoh go to Frank's café to do a project with their classmates and Frank flirts with Ngoh. At home, Ngoh's father reprimands her for going out too late, thinking that she went out with her friends that are bad influences instead of actually doing her project. Frank is seen to be a cheater and sleeps around a lot. Pu, Pam, and Ngoh go watch Yok's dance performance at the mall while Duean continues to work at the café. Yok reveals that his father forced him to cut his hair short and Ngoh makes a shocking revelation.

Pu comforts Ngoh and Yok returns home to his disapproving father while his mother excitedly asks him how his audition went. Ngoh returns home and asks her mother where she was. Duean's landlord sees her mother at the nightclub and Pu goes out with Louis again, trying marijuana for the first time. Ngoh is disappointed with her mother's dishonesty, and Mangkood comforts her. Duean's neighbors call her mother out for being a prostitute and they get into a fight with Pam, Joe, and Duean, ending up with them going to the police station. Pu's mother stays with Lookmoo at the hospital while Wasan and Pom are at home with Pu. Pu's life is drastically upended after returning home and Duean's mother is forced to sleep with the landlord to pay off her rent. Pu goes to school and starts thinking recklessly, with Ngoh being concerned for her safety.

Ngoh comforts Pu after she vents to her. Duean is also consoled by Pam after telling her about her mother's profession and starts to do things in spite of her mother. Pu becomes desensitized and starts taking drugs to numb her pain. After being admitted to the hospital, she goes to live with Louis and Ngoh becomes concerned. Ngoh ditches school and asks Frank for help in finding Pu.

Pu returns home drunk with her mother scolding her. Ngoh also returns home drunk, her father hitting her, drunk as well while her mother and sister fearfully listen. Louis's job is revealed, with the police searching his house. Frank takes Ngoh to a pet shop and adopts a dog for her. Duean tries a new job and Yok confronts a senior he likes at the mall.

Ngoh doesn't return home for the night and faces punishment from her father. Pu returns home wasted, trying to confess to her mother who won't believe her. Pam's father hits her mother after she gambled away some of their possessions. Pu, Ngoh, Duean, Pam, and Yok ditch school to go to a zoo and the beach.

Pu misses school again and Ngoh goes looking for her at the arcade. Duean doesn't show up at work and goes to a different job which makes her mother suspicious. Yok prepares for his dance competition happily but his father locks him in his room, refusing to let him go. Pu, Ngoh, Duean, and Pam trespass into a closed bowling alley and are caught. Pu, Pam, and Ngoh are punished by their parents and Duean confides in Pam.

Pu is kicked out of her house and is forced to find a new place to live. Yok runs away from home and rents out an apartment with Pu. After going to a party, Ngoh returns home drunk again, her father furiously waiting.

Ngoh shows up at Pu's door after being hit by her father. Pam's father finds Pam passed out in front of his house and handcuffs her to the gate. Yok's mother goes looking for him while his father is nonchalant. Pam runs away and moves in temporarily with Pu and Yok. Duean's mother starts to grow more suspicious of Duean.

Ngoh, Pam, Pu and Yok hang out at the mall. Duean vents to Pam again, telling her about her worries. Pu sleeps over at Louis's house, trying heroin for the first time. Pam's father asks Joe if he knows where she is. Duean's mother begs her not to resort to prostitution while she refuses as she wants better treatment for her father. Pu, Ngoh, Duean, Pam, Joe, and Yok go on a trip to the beach, with Pu letting them try heroin.

The police start to become suspicious of Louis and investigate him. They try to crack down the growing heroin business, which is supplied by Louis. Pu, Pam, Duean, Ngoh, Joe, and Yok start to develop a heroin addiction. Pu steals Duean's money to get more drugs and Duean gets angry at her. Pam and Joe follow Duean to her job and Joe tells Pam a secret.

Pam decides to do something drastic and Joe tries to stop her. The police continue to crack down on illegal drug dealers and are closer to finding out about Louis. Ngoh becomes wary of Frank and Yok has a shocking revelation. Duean confronts Pam about what she was doing. Pu and Yok go back to their houses to find money to buy more heroin.

Ngoh starts feeling symptoms of drug withdrawal and Yok makes a drastic decision. The police use one of Louis's customers to lure him and eventually catch him.

Louis is released from jail as the officers struggled to find enough evidence. Pu, Pam, Duean, and Ngoh increasingly struggle with a heroin addiction and Ngoh is admitted into a hospital due to drug withdrawal. They attempt to get money to pay for rent and to wean off drugs by selling clothes at a market. Frank urges Ngoh to go home which she does but her father doesn't let her in.

Pu, Pam, Duean, and Ngoh struggle to sell clothes at the market due to them trying to quit smoking heroin. Louis attempts to find a place to stash the drugs since he knows the police are onto him. Joe starts to show signs of drug withdrawal and begs Pam to help him get heroin.

Louis becomes distant with Pu after receiving some news. Pu starts to miss him and Ngoh consoles her. Pam is back on her heroin addiction and Ngoh, Duean, Pu, and Joe are desperate for it. Pu returns to Kanchanaburi to steal money from her father and discovers he has a new wife.

The main characters reach the peak of their heroin addiction and really attempt to stop.

The story wraps up as the four girls slowly wean off drugs and struggle with drug withdrawal.