In the family everyone becomes a suspect.
The story revolves around an extended Thai Chinese family whose members' seemingly happy relationships devolve into conflict following murder of the eldest son and head of the family business.
The Jiraanant family gathers to celebrate the birthday of the family patriarch who is also the head of a lucrative family business. While the family gives their wishes to Grandpa Sukit, tensions are also present amongst other members of the large family.
Following the death of Sukit Jiraanan, the will of the family patriarch is read by the family. Patasorn feels jilted by the content of the will and threatens to her brother Prasert that if he does not sell her one of the family hotels she will quit and take all of the staff with her. Meanwhile, Prasert's son Pete returns to Hong Kong, the new owner of 25% of the family's company shares. Prasert pays a visit to Nipha and their son, Pharada.
After Patasorn found her brother dead from a fatal shot to the stomach, the police are called to investigate the scene. Patsorn is a quick suspect after her public fight with Prasert just before his death. Fearful that his mother may relapse in her health treatment if she learns the news of Prasert's death, Pharada tries to disconnect her from local news sources.
Patasorn's sons rally around her and netizens and the media are quick to cast judgement on her involvement in her brothers death. Pete learns a shocking truth about his parents relationship while being questioned by the police.
Pete takes an opportunity to meet with his fathers other family.
Yi sneaks into the Praset household to investigate the murder to clear his mothers name, in the processing finding 20 years worth of photos of Praset with his family on the side.
Detective Somphong initiates a bidding war between Pete and Yi to see who will pay more for compromising photos of Cris with Prasert's gun.
Tao stumbles through an interview with the press, trying to defend his mother. The fallout from the interview forces Phatson to make a public appearance for the first time since the murder.
Phatson's situation with the switched pants on the day of the murder draws new suspicion, including from her own family. Pete arranges for the reading of his fathers will in the presence of his mother and Chi.
After Toei finds Meimei holding the gun in her room, the two enter into a secret pact to dispose of the evidence and keep the secret between them.
Meimei denies the claims that Toei has relayed to the police about the events on the day of the murder. The suspicion landing fully on Toei, he is arrested to avoid the destruction of any more evidence. An additional search Meimei's room by the police results in the discovery of the hidden camera inside the teddy bear gift from Toei.
Mate considers turning himself into the police, but Meimei holds him back. Vegas retrieves the recovered CCTV files from the repair shop. Kuaitiao introduces Yi to Sukrit's sketchbooks as a way to uncover their family's hidden past.
Nipha finally learns that her husband is not abroad in America, but has been murdered. Pete meets with his late father's lawyer to investigate the will and why his father would leave nothing for his wife and son Chi.
Yi, with the help of Toei, Vegas, and Kuaitiao finds the missing red sketch book and uncovers a buried family secret that seems to be connected to Prasoet's murder.
Meimei and Mate flee to Hong Kong when Vegas reveals to them that Yi has learned to truth about the murder. When Ern finally reveals that he has kept Phatson's bloody pants, Phatson is faced with a heavy decision in a last attempt to save Toei from prison.
As the trial date approaches for Toei, Yi rushes to Hong Kong to meet with his estranged relatives, Mate and Cris.
Mate stands trial for murder with Meimei as a key witness. The family worries about Meimei's new reality in the aftermath of the trial.
As the dust settles following the trial, Pete extends the first olive branch to return peace in the family. Phatson tells Pete everything about how Pim was poisoned to put the matter finally behind them.
