Opening in a courtroom, the first episode of "Phantom Lawyer" reveals a ghostly whisper that prompts attorney Shi I-rang to accuse the witness of being the prime suspect. A flashback to a year earlier introduces us to I-rang, an ordinary lawyer struggling to secure a job, but repeatedly rejected by every firm he interviews with. His dream is shattered when he receives a blatant rejection from Taebaek Law Firm, delivered by Partner Han Na-hyun, who candidly states that his father's past actions 20 years ago are the reason for his rejection.
It is revealed that his late father was a prosecutor accused of corruption, which has resulted in his CV being marked red by law firms, meaning none of them are willing to hire him. Frustrated and angry, I-rang spends a night ranting to his friend about the unfair treatment he's received since he never did anything to get himself blacklisted. He makes a bold decision to start his own law firm. His friend had suggested he change his name, but he decides to start a company in his own name, vowing to make all those who had looked down on him beg to serve him.
On his way home, he passes by Mr. Kim's real estate firm and impulsively decides to rent an office space. He withdraws 30 million from his mother's deposit, and Mr. Kim tricks him into renting a haunted room previously occupied by a shaman who had just collapsed. I-rang is initially skeptical about the room, but the view of the court offices from the window convinces him to proceed.
As he sets up his new office, I-rang finds incense in one of the drawers and lights it. It causes him to fall asleep, and when he wakes up, he encounters a ghost. He learns that a Shaman previously owned the place and tries to back out of the deal. However, Mr. Kim blackmails him by threatening to tell his mother that he used part of her deposit to rent the place. I-rang has no choice but to keep the lease.
In this vividly described scene, we see I-rang's journey from being an ordinary lawyer struggling for recognition to becoming a determined individual who will not let past mistakes hold him back. The encounter with the ghost adds a supernatural element to the story, making it even more intriguing and engaging for viewers.
The ghost, Lee Gang-pung, begins to haunt I-rang relentlessly, even in the safety of his own home. During a family dinner, the ghost possesses I-rang, forcing him to consume pork despite his severe allergy. In a desperate attempt to break free from the ghost's grasp, I-rang seeks the guidance of a priest. The priest advises that by discovering Gang-pung's name and date of birth, they may be able to help him remember his past and ultimately release his spirit from its earthly bonds.
With the priest's assistance, I-rang embarks on a quest to uncover the ghost's identity. Through meticulous surveillance using CCTV footage, they manage to track down Gang-pung's wife, Kim Min-ju. Shortly thereafter, Min-ju visits the law firm in search of the shaman who had helped her when Gang-pung collapsed. Her concern for her husband prompts her to seek out I-rang at the rental office.
Min-ju shares with I-rang the story of her husband's death and the subsequent isolation of their daughter, Ji-woo, who has been locked in her room for six months. This heartbreaking tale motivates I-rang to take action. After learning Gang-pung's name and date of birth, I-rang discovers that the ghost's memory has been restored. The overwhelming desire to embrace his wife causes Gang-pung to possess I-rang once again, leading to a chaotic misunderstanding that ends with Min-ju slapping I-rang in confusion.
Gang-pung then enlightens I-rang about his true circumstances, revealing that he did not die of a heart attack as initially reported by the doctors. Together, they embark on an investigation, utilizing Gang-pung's ability to go unnoticed to eavesdrop on conversations and follow Min-ju's lawyer. They uncover a scheme orchestrated by Taebaek Law Firm to convince Min-ju to settle.
I-rang exposes the scheme and convinces Min-ju to let him help for the sake of their daughter, Ji-woo. I-rang's family is thrilled by his first trial, and they show up in court to support him. However, Gang-pung's continued presence and the weight of his family's expectations add to I-rang's already mounting pressure. The tension in the courtroom is palpable as I-rang battles against time to right the wrongs done to Gang-pung and his family.
As the trial commences, Na-hyun summons the defendant, Doctor Lee Jeong-seok, to the stand. Initially, she assumes it to be a straightforward case and presents only the doctor's report on the cause of death as evidence. However, when I-rang engages in cross-examination, he reveals a shocking revelation: contrary to the report, three nurses were assisting in the surgery, and Jeong-seok had lied and paid to silence the key witness, nurse Oh Jin-suk. Although I-rang is unable to bring her forth as a witness, Jeong-seok's facial expressions at the mention of her name are undeniable proof that there's more to the story.
To salvage the situation, Na-hyun shifts her tactics and begins to attack Gang-pung's character. She presents pictures of his past as a gang member, revealing that he had a previous injury around the heart and was prone to cardiac arrest. She further alleges that he was rude and violent, even towards his own family.
The episode culminates with Gang-pung's rage due to Jeong-seok and Na-hyun's lies, leading him to possess I-rang. He creates a scene and almost attacks Jeong-seok but falls after Na-hyun trips him.
