Naughty Dirty Troll has some very disgusting habits. It is not only Naughty Dirty Troll who falls ill, but his friends do too. Luckily Sister Duck the nurse is on hand to make everybody feel better and Naughty Dirty Troll's friends teach him about taking care of his personal hygiene. This book is bilingual English-Chinese and the two languages complement each other rather than simply serving up a translation. In this way, the child is encouraged to learn both languages in order to fully appreciate the story. The story itself aims to teach children about their role in maintaining basic public health and the importance of personal hygiene and brushing their teeth.