Dan is a pleasant 16-year-old boy who has had a very unfortunate life. His parents died when he was a child, and his aunt and uncle took him in. They didn't really want to do this, but by doing so they could claim Dan's parents' house. Dan has grown up in the house with his aunt, uncle and their son, Robin, who is the same age as Dan. Robin is an obnoxious and spoilt child. He is as cruel as his parents are to Dan. Dan is treated like a servant in his own house. But what can he do?
At school, Dan is having problems too. He has fallen for a girl (Elsa) who already has a boyfriend (Sam). Things become worse when Dan is made the official school leader. Sam wanted to be the school leader and takes it personally that Dan stole his glory. To make things worse, Sam doesn't like the way Dan acts toward his girlfriend, Elsa. He always badmouths Dan to her, causing her to hate Dan. Dan also has an admirer (Rosy) whose love is unrequited like Dan's.
Fortune takes a funny turn one night, when Dan is starting to sleep. He feels as if he is under a spell, during which he is guided to a beach. At the beach, a mermaid called Dewi Tirta gives him a ring. She gives him the ring because he has a pure and sincere heart.
Dan soon finds out that the ring has magical powers. When he wears the ring he becomes invisible. Dan starts to use his new powers to take revenge against the people that have been mean to him. His aunt and uncle become convinced that "the mango tree ghost" haunts their house from their garden because of Dan's antics.
But the ring has a history. In another world there are a group of creatures that are ruled by a Black King, who wants the ring back. The ring is the one thing he needs to control the mortal world. With a magic ball they have located the ring, and the boy who has it. The Black King sends Prince Kelam to the mortal world to obtain the ring. Kelam masquerades as one of Dan's schoolmates to get the ring back.
How long can Dan keep the ring? How will he fight against strange powers that want to rule the world?