Plot

Phaya visits a friend to learn more about the Naga and Garuda legends.

Episode 6 of The Sign starts where we left off, with Phaya's dream about Tharn. A knock on the door from his little sister wakes him up, and he immediately calls Tharn to ensure he is okay. Tharn is chilling at his condo, swimming with Khem and Thongthai. Phaya suggests that Tharn take some time off work for his safety, but Tharn refuses.

Phaya decides to go out and see Tharn when he refuses to pick up his calls, but his friend Dao arrives, and he has to join them for dinner. Meanwhile, Yai joins the group at Tharn's house, and they start teasing Tharn about him and Phaya being more than colleagues. Khen starts telling the story about the first meeting between him and Thongthai.

In a flashback to 2009 in some university, Khem tries to show off his swimming skills and abs to a group of admirers, but a more famous swimmer appears, ruining his thunder. He gets off the pool, and suddenly everyone starts screaming, and he takes some time to realize that he lost his swimming suit in the pool and is walking butt naked. He jumps back into the water and knocks Thongthai, who is walking behind him, into the pool.

Later, he gives him his swimming clothes since his uniform got wet. Khem starts going after Thongthai, who keeps insisting that he does not like men but later gives in, and they start their relationship by knowing each other intimately in bed and talking later on.

Back to the present, Thongthai suggests that Tharn adopt their method and get intimate with Phaya to determine if he likes him that way. Tharn insists that he has no feelings for Phaya. After leaving the room, Khem suggests taking a trip to give Tharn and Phaya a chance to figure out their feelings. On whether Tharn has ever dated before, Yai tells them that he dated someone but died, which made Tharnm afraid of love since he does not want to go through such type of hurt anymore.

During dinner, Dao tells Phaya's grandmother about his injury and suggests making him quit his job as a police officer. Phaya's grandmother declines, saying that Phaya has always wanted to be a police officer, and as long as he takes care of himself, she has no problem with his work. Dao advises Phaya to find a better work-life balance and ensure he cares for those who need him.

His little sister seems interested in Dao, and after dinner, she goes to Phaya's room to ask about her. She wants to know if they dated when they were studying abroad and is relieved that their relationship is nothing more than brother and sister.

Phaya decides to visit her sister's friend, Wi, since she knows about archaeology. He asks about his dreams and the legend of Naga and the Naga fireballs and wants to know if the legend could signify that the creature existed. Wi tells him that any proof they might find would be proof of the creature, which is not a human being. She adds that there is hardly any record of the presence of the Garuda, the half-human and half-bird creature he saw in his most recent dream. He might find stories from religious mythologies that would be difficult to prove if they are real or not.

However, she can tell him from her scientific point of view, but if science cannot prove something, it does not mean the stories are false. Since the stories are being told, then it means that someone recorded something they had seen. Wi sends Phaya to a private room in her gallery where she keeps records of ancient things to look around and see if anything will be important to his research.

Phaya is attracted to a certain book on the top shelf of the room, and when he touches it, he starts having flashbacks of another era where he sees himself and Tharn. In the flashback, he is a half-bird, half-human creature fighting with a Naga when he gets injured. He is in his human form when Tahrn finds him and calls him King Garuda. Phaya is badly injured, but Tharn heals him.

In another scene, they watch the fireballs together. Tharn explains that on the 15th day of the 11th moon, the Nagas, the Naginis, and their attendants present offerings and breathe out the fireballs as an act of worship. Phaya and Tharn kiss in his flashback, and then Tahrn refuses to go with Phaya, saying that he does not want anyone to die, and a Naga is seen chasing after them. Before Wi calls him to wake up from the floor, he hears Tharn calling him Master Sakunanoparug and stretching out his arm full of green scales to pull him out of the water.

After he wakes up, he sees a drawing of the son of the Naga City Governor, and he looks so much like Doctor Chalothon. Phaya borrows the book from Wi and goes to look for Tharn. He finds Tharn leaving for dinner with Chalothon and goes to stop them, but Tharn does not want to go with Phaya. Chalothon locks Tharn in his car and tells Phaya that he will do anything to keep them apart, even if it means killing Tharn.

Phaya gets angry and punches Chalothon. Tharn gets out of the car, and when Phaya tries to pull him away from Chalothon, he punches him and then leaves with Chalothon. On the way, he apologises to Chalothon and says he will stay away from Phaya.

The next time at work, inspector Akk gives the team a mission of a protection detail in a gallery and asks for volunteers since it is not an official mission. The team thinks there is a hidden agenda since this is the first time they have taken a mission like this and are going undercover. Mayris tells them she will not join since the inspector wants her to find information on Lieutenant Tam's case.

The boys are surprised to learn that Lieutenant Tam was the deputy at the special investigations unit and one of the best spies tasked with uncovering the drug trafficking network believed to be run by a politician, Minister Montree. Tharn wonders why they cannot just question Songyod, who is in their custody and believed to be linked to the drug network, but Sigh and Mayris explain that their unit only has permission to investigate without crossing the line. Hence, they can only work on approved cases and not go beyond what they can.

Mayris calls it "fake freedom", meaning they can go forward, but only in the direction their superiors allow, which leads to many unfair case closures, including the case of Lieutenant Tam and Tharn's parents case.

The gallery event Inspector Akk asks the team to protect is the same one Dao invited Phaya, his grandmother, and his sister, and they run into each other. Phaya introduces Yai and Tahrn to his grandmother and invites them for a meal at her house when they have some free time.

Phaya runs after Tahrn to apologise for what happened in his condo. Dao interrupts and Tharn excuses himself. When Phaya goes after Tharn again after showing Dao to his grandmother and sister, he sees him with Chalothon and decides not to follow. Next, Tharn and Yai watch the attendees through a window, and Tharn cannot take his eyes off Phaya and Dao.

Yai asks him not to deny his feelings and agrees to date Phaya. If he is afraid that Phaya will be in danger, Yai promises to help Tharn protect Phaya. At the end of the episode, Tharn bumps into someone, and something drops. He bends to help him pick it up, and when their fingers touch, Tharn has a vision about a possible murder at the gallery.