The Secondary 2 boy returned home on the eve of National Day with a swollen jaw and a small cut under his eye. He claimed they were from a fall.
His parents were sceptical, but didn't question him further.
By the next day, Adam, 14, (not his real name) was still in pain. His father took him to Changi General Hospital (CGH) and was shocked to find out that his son had a broken jaw.
Adam later confessed to his father that he had been involved in a fight.
He had gone to see a movie at North Point Mall with a friend when a Secondary 4 boy asked Adam for a meet-up at a fast-food restaurant in the mall after the movie.
When he arrived at the meeting place alone, Adam was hit by the boy and another Secondary 4 boy.
He claimed that one of them hit him on the chin, while the other punched him in the eye.
Adam claimed that he didn't know why they hit him and could not remember their conversation before he was beaten. He knows the two boys because they attend the same school in the north.
After the beating, Adam took a bus and reached home at about 7pm.
He was worried about his father's reaction to his injury and tried applying ice to lessen the swelling. It didn't work.
His father called The New Paper about his son's injury on Monday morning.
He said: "I know teenage boys are playful, but it is too extreme to beat up my child to such an extent."
Adam, who is slim, had to undergo nearly six hours of surgery to fix his jaw, which had been broken in two places. He was in the Intensive Care Unit for a night after the surgery.
His mother was heartbroken.
She said: "He was a weak baby and had gone through two operations, including a heart operation, when he was younger. He's had problems with his heart since birth.
"I felt like I was going through the whole trauma again."
Adam had already been moved to a normal ward when TNP visited him at CGH on Monday. But he still could not speak or eat solid food because of the surgery.
The once bubbly boy, who could only drink milk since Friday, mumbled weakly that he wanted to eat a McSpicy burger when he recovers.
Adam was discharged on Monday night and will be on medical leave for 21 days.
His parents alerted the school on Tuesday and have spoken to the aunt of one of the attackers.
The school told TNP that it takes a serious view of the incident and is in contact with the parents of the students involved.