An elite school known as Saint Mason Secondary School was a private school since 18 years ago. Although it was well-known, it also has a few tragedies regarding about the old building.
Saint Mason's Secondary building was built-in the year 2006. The structure of the building was plain and it had four washrooms, two for the girls' washroom and the other two for the boys' washroom.
Saint Mason's Secondary building was well-known for the infamous haunting of the girls' washroom. However, it has one terrible incident as two couples who were the students of Saint Mason School were brutally killed one month ago.
Three months later, the former students of year 11A organized their school reunion for their class. The first person arrived was Chen, a young girl who lives at the terrace house behind Saint Mason's Secondary building. While waiting for her friends, she decorated the whole classroom as a preparation.
After few hours of waiting for Chen's classmates, Rafie, one of Chen's classmates arrived along with his two friends, Qawi and Rusydan. As few minutes passed, Shirley, Agnes, AJ, Brynner, Jia Xin, Shin, Winnie and Branden were the only ones attending the reunion. Although it wasn't enough for 12 students, but she felt touched that some of her friends would willingly to come.
As night falls, the reunion for the year 11A has commenced, the music beats filled their classroom with full swing and thus everyone went crazy with their smiles on their faces. Qawi mix the music so that the beat can be enjoyable for dancing, Rusydan and Rafie drank a bottle of soda as a challenge to entertain the students, Brynner and Branden compete each other with the game "Tekken 6" on PSP.
The atmosphere in 11A room went great, as Shin took out a game of "Twister", Winnie and AJ were excited and thus they joined in the game with Shin. While the others were enjoying themselves, Jia Xin, Agnes and Shirley talked about life after the year 11 and Chen contacted her best friend, Lee Ling and asked her if she could come for the reunion.
While Shirley was talking with Jia Xin and Agnes, she received a call from her sister, Lily. Lily called Shirley and asked her if she could get her forgotten textbook in room 9. At first, she denied, but as Lily pleaded her, she hung up her phone and head outside the corridor to room 9.
As Shirley arrived to the room 9, she opened the door and saw a man sitting on the teacher's chair, with chains hidden under his lab coat. With curiosity, she looked closer to the man to find out his identity. But as she stared at his face, the man grabbed her and threw her against the wall. Shirley went terrified and struggle to get out from the room.
However, Shirley couldn't run away from the man as her legs have been chained. The man gagged Shirley's mouth so that she couldn't scream. He then tied her hand and took her to the door. After he placed her, he violently slammed the door repeatedly and brutally. Shirley tried to scream in pain, her pain of being tortured is beyond her agony.
The man finally beheaded Shirley as he slams the door with a great force. The blood spewed out and creates a puddle of blood, and it also stained the man's lab coat. He then used Shirley's blood, heads outside the corridor and wrote "Yours Truly, Shirley's Worst Nightmare." As he finished writing his mark, he heard a cell phone ringing. He took the phone, and destroyed the phone by threw it on the floor.
Meanwhile, Jia Xin and Agnes felt uneasy and worried about Shirley; Chen came in between the two and told them to enjoy themselves. As they tried to enjoy themselves, Agnes called Qawi and asked them if he can look out for Shirley. Without hesitation, he heads out to the corridor and looking out for her.
The man, who claimed himself Nightmare, he wear his mask and took several inches of steel chains, while he was looking for his machete, he saw Qawi, who stared at Nightmare's mark. Nightmare didn't have time to take his machete with him, so he took a fully loaded stapler and ran towards Qawi.
As Qawi saw the masked man running towards him, he tried to run from him, but Nightmare finally immobilized him and violently stapled Qawi's neck while covering his mouth to prevent him from screaming. After repeatedly stapling his neck, Qawi finally died, with several staplers pierced on his neck.
With the absence of Qawi and Shirley, fear has developed within the student's mind. With fear in AJ's mind, she went to the boys' washroom, which is close to their class. As they waited for Qawi's and Shirley's return for hours, year 11a's fun reunion has become a silent nightmare.
As Chen become scared, Brynner tried to comfort her and asked Rusydan if he could find both Qawi and Shirley. Though scared, but Rusydan willingly find them. So he went look for Shirley in the girls' washroom. As he arrived there, he find nothing and decided to go back to the classroom.
However, at the exit from the girls' washroom, Nightmare awaits Rusydan. He was stunned as he saw the blood stain all over Nightmare. Nightmare took his opportunity and slammed Rusydan's head against the wall. He then forced him to the toilet and drowned him until he died. As he finished, Nightmare left Rusydan's body behind and look for his remaining targets.
After several minutes of waiting, Agnes felt enough and wanted to go home, as he went outside, she saw Nightmare on her left. He punched her Agnes in the stomach and took her cutter from her, finally, he started to stab her violently until she died.
The 8 remaining students terrified as they tried to escape through the back door. The group hide themselves in the science lab and hoping that Nightmare won't find them. As they tried to call for help, they recalled that they left their cell phones behind while they were running from Nightmare, and thus they felt like being left alone in their horrifying nightmare.
After sleepless hours waiting for daylight, AJ felt enough and headed to the computer lab to find help. However, Chen denied her and pleaded her to stick together. But AJ told her that she will definitely okay and left the lab.
As AJ went inside the computer lab, she tried to look for a telephone so that she can call for help. After searching with no luck, she left the computer lab. Suddenly, Nightmare came out and strangled her with cables. He used his force so great, that even blood spewed out from AJ's mouth. As he finished, he left AJ's body and look for the others from room to room.
After searching all the rooms in one corridor, Nightmare went into the science lab. Chen and the others were hiding in the other room, waiting for Nightmare left the lab. As he intend to leave lab, Jia Xin sneezed, and with quick haste, Nightmare finally caught Jia Xin. She screamed for help, the other 6 students tried to help her, but Nightmare destroyed the door and threw Jia Xin against the cabinet.
As Chen and her friends saw Nightmare, they were terrified. However, Branden took a bottle of hydrochloric acid and threw it against the floor, causing it reacts with the marble floor and produces steams to fill in the room. So the group took the opportunity and escape.
Depressed and unusual, Nightmare destroyed all the apparatus inside the lab until he discovers that Jia Xin is still alive, so he took four power supplies and placed Jia Xin on the table. Then he tied her with his chains and electrocuted her until 12 volts in every power supplies.
While running from Nightmare, Rafie felt tired of running because of the drinks he had. So he hide in the primary classroom and rest for a few minutes. As he finished taking a rest, Nightmare appeared ahead of him and stabs his abdomen with his machete. However, he had his remaining strength to drive Nightmare off and escape to reunite with Chen and her friends.
Although Rafie would be able to catch up with his friends, Nightmare managed to slipped Rafie with his chains. As Rafie begs for mercy, Nightmare remained silent and slowly stabbed Rafie's chest into his heart. Chen saw what Nightmare did and she wants to turn back for Rafie, but Brynner told her that it is too late for him.
After several hours running and hiding from Nightmare, Winnie and Shin ran away from Nightmare and got split up from Chen, Brynner and Branden. As they hid in the staffroom, Shin asked Winnie if everything is safe to come out. However, Winnie doesn't want to go out alone, but when Shin tried to comfort her, she finally faced her fears to go out alone.
As Winnie opened the door, Nightmare appeared and put his palms into Winnie's mouth. As he forced Winnie's mouth to open wide, her face ripped off with blood spewed out on Nightmare's mask. As Shin heard the horror, she screams and throw things at Nightmare.
However, her efforts for defending herself unsuccessful. As Nightmare closes in on her, he chained Shin's legs and hung her upside down. As he struggles, Nightmare instantly killed Shin by slicing her neck with one slash using his machete.
As Shin and Winnie died under Nightmare, Chen, Brynner and Branden ran in the corridor for their lives, thinking that Nightmare is still after them. As they found the exit, Nightmare's machete flew towards Branden's chest and Chen shrieked in terror.
As Branden were pulled into the darkness of the front office, Nightmare hold and finished him off by plucking out both of his eyes, poke violently on both of his ears and cut out his tongue. As Branden lost all of his 3 senses, he ran aimlessly until Nightmare stabs him in the chest and pulled out his heart. As he finished his tyrant killing, he then chase after Brynner and Chen who were trying to get out.
Unfortunately, while Nightmare was chasing after Chen and Brynner, Lee Ling finally arrived which interrupted him. So Nightmare decided to deal with the intrusion and later search for Chen and Brynner. Meanwhile, Lee Ling felt strange and disturbed as the atmosphere for the reunion went gloomy.
Suddenly, Nightmare jumped down behind Lee Ling. Before she could even turned her back, Nightmare stabbed her in the face, giving her an instant death. As he finished her off, Nightmare left Lee Ling's body and continued his search for Chen and Brynner, the last two remaining targets.
It was 3.38 AM, Chen and Brynner hid inside the accountant room. As Brynner told Chen that they should get out of the school and expose the event they have witnessed, Chen agreed and the two went to the maintenance room to take any useful tools to open the locked shutter from the entrance door.
While Brynner and Chen were gathering the tools, Chen screamed as Nightmare appeared far behind distance from them. With a quick move, Brynner threw a hammer at Nightmare, which made him unconscious. As they finished gathering the tools, they rushed towards the lobby and quickly unlock the shutter.
As Nightmare gained his consciousness, he wrapped his long chains around his left hand and walk towards Chen and Brynner. As the two finally opened the shutter, Chen went out whereas Brynner went out last. Unfortunately, His leg was chained and Nightmare won't let him escape.
As Nightmare approached the lobby, Brynner were busy struggling desperately to get out. After Nightmare saw Brynner's struggle, he closed the shutter with great force which beheaded him. Chen painfully witnessed the moment as she saw her best friend beheaded by a psychopath. Chen managed to get outside the gate, which thought that the nightmare has ended.
As Chen ran towards safety, she fell down and felt that her leg was being pulled. As she turned her back, she saw the masked, blood covered Nightmare, staring faintly at her. As Nightmare gave her a head blow, she felt unconscious.
As Chen woke up, she was hanged upside-down in a hauntingly familiar room. As she wait for her fate, Nightmare went inside the room as he prepare his machete. Before Nightmare could start, Chen asked Nightmare for the reason behind his senseless kills. Nightmare paused, and then he wrote his answer in blood, "Your cursed persecution killed me, I will have my revenge."
Without mercy, Nightmare skinned Chen slowly without any guilt or remorse. Chen cried in agony as Nightmare flayed her slowly. As he finished skinning Chen's whole skin, he left room 10 and left Chen alone. The next day, a shocking new has been heard as all 13 former students were brutally murdered in one night. The police confirmed that the case was left unsolved. As they investigate room 10, they sighted Nightmare's mask, which tells the story behind his motives.