Wang (Wen Jun Hui) is a twelve-year old kid with learning difficulties. He is not a mute but has never spoken a single word. His mother has been telling him that his father had flown to a remote place. She kept on praying to a plastic flower and said, "One day the flower blooms is the day your father comes back." When Wang was six, he watched his mother jumped from the balcony. He thought his mother has flown to find his father.
A young and weird person, Dui (Eason Chan) arrives to Wang's school and takes up the job as a janitor. At the same time, a substitute teacher Miss Cheung (Gia Lin) arrives who is also a weird person. Sparkle ignites when these three weird people bump into each other.
Wang's father, being the rising star in the triad, is back from overseas to expand power in Hong Kong but with a real attempt to get Wang back. Threatened by his rising power, other triad leaders resort to kidnap Wang and assigned Dui with this task. Wang's father is not a fool, he had already placed a bodyguard who is a formidable sniper close to Wang, and this sniper is Miss Cheung. Without knowing each other's real identity, a warm relationship develops among the three. Miss Cheung has feelings on Dui and in truth, they are just like a family.
Christmas Show is coming, Wang announces that he will sing a song for Dui and Miss Cheung on the stage. But Dui discovers that the triad's leaders get another new plan – to assassinate Wang's father. To ensure Wang a happy life, Dui makes his first decision in his life – to rescue and protect Wang's father. In the midst of Wang's singing, a bloodcurdling battle in the school also begins...