The Investigation Detective Force is working on the case of a kidnapped man named Michael. His young daughter is left behind as a witness to his kidnapping. Tharn and Phaya are tasked with protecting his daughter while the rest of the team searches for Michael, but their plan fails, leading into a rescue mission instead.

IDF moves forward with their mission to arrest Montree. Phaya and Tharn face off with Chalothorn for the final time. 

Phaya and Tharn investigate the missing person case and the reports of a "tiger-man" in the woods. 

Phaya and Tharn return to visit the Abbot during Tharn's suspension from work. A witness comes forward with evidence related to the case involving Montree. 

Phaya is in critical condition at the hospital after the incident at the river. The rest of the investigation team looks for additional clues in the case and the connection to Lt. Tam. 

Phaya learns the truth about his connection to Tharn and their tied fate. 

Phaya and Tharn's team investigate a missing person's case after an incident at the art exhibition. 

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

Phaya and Tharn make an arrest in the investigation into the serial killer case. 

Phaya, Tharn, and Maris return to the crime scene to search for more evidence into the serial killer.  A conflict arises between Phaya and Tharn after a dinner with Chalothon.

Seeking answers about his visions and dreams, Phaya returns to the temple where he first met Tharn and Yai as kids. 

Phaya, Tharn, Yai, Khem, and Thongthai buckle down and commit themselves to passing the special forces exam after getting disciplined for their investigation into Lieutenant Tam's suicide.  

Phaya and Tharn work hard to complete the training to enter the special forces police unit.  During the training, both experience unique visions related to each other. 

Follow the cast and crew of The Sign behind the scenes as they discuss their characters and the filming process.