Redhill Tragedy: Emman, Time Traveller

Emmanuel was in school when he received a strange visitor. It seems that no one but Emman could see the boy who was dressed in an old-fashioned Malay outfit. When Emman approached him, the boy 'spoke' to Emman telepathically to tell him that he was The One. When Emman asked him The One what? The boy said, The One to save him. The boy made an urgent plea to Emman to help him, then dashed away hastily. A magic portal opened up and the boy stepped through it and disappeared.
Before he left, the boy had told Emman to attend a talk called The Redhill Tragedy. Curious, Emman searched online and found the talk to be at the National Museum. He asked his Peranakan, paternal grandmother to attend with him. The talk was about a boy Nadim, who was killed in the Redhill Tragedy. Suddenly, the boy Emman saw before, appeared again, telling Emman he was Nadim. He persuaded Emman to save him.
But what could Emman do? Nadim had lived and died in the 14th century Singapura. How could he undo history? And how would he be able to get back to the 14th Century to prevent Nadim's murder? When he posed his dilemma to his Grandmother, Grandma surprised him by telling him that she can show him a way. But first he must have the courage to accept the quest.