A part-time cleaner took part in her friend's plan to seek revenge on a pair of siblings and boiled some water which was used to cause second-degree burns to the two victims.
Nurhanifah Juma'at, 27, also filmed the assault that lasted about four minutes, moving from place to place to capture different angles.
She was sentenced to one year and three months' jail yesterday after pleading guilty on Jan 3 to one count of voluntarily causing hurt by dangerous weapons or means.
It all started on July 7 last year when Nurhanifah agreed to her friend Norhayati Jaffar's revenge plan. The 35-year-old woman was angry after watching a video clip on Facebook which showed her younger brother, Mr Muhammad Putera Shafiellah Jaffar, being beaten up by a group that included Mr Muhammad Faizal Omar, 27.
The court heard that Mr Faizal's sister, Ms Nur Farahtika Omar, 25, had looked on while the group ganged up against Mr Putera.
Norhayati then hatched a plan to take revenge.
Deputy Public Prosecutor Sheryl Yeo said Norhayati invited Mr Faizal and Ms Farahtika to her home, saying that it was for a Hari Raya celebration and she also had something urgent to discuss with them.
Court documents did not reveal the nature of Norhayati's relationship with the siblings.
Norhayati told Nurhanifah to boil some water and roped in her other younger brother, Muhammad Bakhtiyar Jaffar, 33, to take part in the assault.
When Mr Faizal and Ms Farahtika arrived at the Spooner Road flat near Jalan Bukit Merah on July 8 last year, Norhayati locked the gate behind them and started the attack with her brother. Norhayati repeatedly hit Ms Farahtika with a bamboo stick and stomped on her abdomen.
The court heard that Bakhtiyar rained blows on Mr Faizal even while he was curled in a foetal position on the floor.
Norhayati also used the hot water to scald Ms Farahtika on her neck, back and right ear before striking her neck with the water jug.
After Ms Farahtika escaped, Norhayati joined Bakhtiyar in his attack on Mr Faizal using a bamboo stick, the court heard.
Mr Faizal was also scalded with hot water on the left side of his body before he managed to get away.
Court documents did not mention how he and his sister managed to get out of the locked flat.
The outcome of the case involving Mr Putera's assault was not mentioned in the documents.
The cases involving Norhayati and Bakhtiyar are still pending.