Tracy and Cam often argue about anything, including Tracy's new school, where she has a ghastly class teacher, whom she has christened Mrs "Vomit" Bagley. She hates her. Most of her classmates spread rumors about her mum leaving her on purpose. Tracy says that her mum has to leave because she is a movie star in Hollywood. Tracy decides to exclude herself and go to her own secret house. After a few days she discovers she's not the only one who excluded herself from school as she meet two new friends, Alexander and Football. Alexander is a feeble little boy, whereas Football is the complete opposite, very burly, strong and large. Like Tracy, both boys have family problems: Alexander's dad hates him, and Football has a mother who is always going on at him; his dad has left, and keeps promising to take him to a football match, but he never does. They all stay at a secret house and play dares day after day, including one where Tracy hangs her underwear on a tree. But when Alexander has a go he falls of while football and Tracy are lying in a bed, they realised when he lies cramped and stiff on the floor, even football agrees to help him Tracy looks astonished but still agrees to help.
Suddenly, Tracy's mum, Carly, appears out of the blue, saying she wants her back. Tracy is allowed to stay with her for a weekend, where her mum showers her with expensive gifts. Cam is upset about losing Tracy, but Tracy is hell-bent on going to live with her mother forever.
However, when she goes to her mother's for a second time, her and her mum have a great time for a while until her mum leaves her on her own for hours and hours while she attends a karaoke night at her local pub. Tracy feels frightened and anxious, remembering that this is what her Mum used to do when she was younger. When Carly eventually comes home she is accompanied by a man. They were obviously planning to get passionate, but Carly has to cancel their plans when she remembers Tracy is there. However, before he leaves, she arranges to spend the following weekend with him instead of Tracy. Tracy runs away, eventually choosing to live with Cam, who has always taken care of her.
- Tracy Beaker - The story's main protagonist and narrator; Tracy is daring, bold and reckless. Her previous home was in a child-care house, which was nicknamed "The Dumping Ground" She's currently under the foster care of author Cam Lawson and aspires to be a writer too. She dislikes her school and living under Cam's simple, practical lifestyle and wishes she could wear designer clothes and own expensive gear to be popular.
- Cam Lawson - Tracy's foster mother. She fell in love with Tracy's histrionic personality but Tracy does prove very difficult for her to handle, and the pair often end up quarreling. Cam leads a casual lifestyle, with plain clothing and a short haircut, and Tracy wishes for her to be more glamorous like her mother. She's also a struggling writer. She is proven in the end to care and love Tracy much more than she appeared to. She calls Tracy's room the "Bat Cave" because it is black and has bats in it, and also due to the fact that she suspects that Tracy may be a costumed crime fighter.
- Alexander - A boy whom Tracy befriends at the secret house in which she plays truant. Although Alexander is intelligent, he plays truant because he is teased by the other boys at his school for being hopeless at games. He is terrified of his father, and believes he hates him.
- Football - Another boy who Tracy befriends, Football is the very opposite of Alexander: big, burly, strong and (as his name suggests) mad about football. He and Tracy become friends when she tells him of what it's like to be in care. Football is excluded from school and hates his uncouth mother. He initially speaks very highly of his Dad, despite the fact that he never fulfils his promise to take him to a football match. Eventually, when he sees for himself that his Dad prefers to spend time with his promiscuous new girlfriend, he turns against him.
- Carly Beaker - Tracy's real mother, who turns up unexpectedly after years of leaving her daughter in care. She is blonde, attractive and glamorous, and treats Tracy to a lot of expensive presents during their first weekend together. However, she has very little maternal feelings for her daughter and tends to choose men and boozing over Tracy. When Tracy realizes this, she leaves her mother for good.
- Mrs. Vomit Bagley - Tracy's middle-aged teacher. She is described as having minty breath and an awful "instant-powder, talcum" smell.
- Roxanne - A poisonous girl in Tracy's class at school. Roxanne is constantly making fun of Tracy (specially because of her clothes). She is described as "playing Little Miss Innocent" in front of teachers but can be as daring as the protagonist.
- Mr. Hatherway - The reception class teacher at Tracy's school. He is the opposite of Mrs. Bagley, and Tracey seems to like him, and regrets that he'll never be her teacher.
- Trevor - A young child whom Tracy meets when Mr. Hatherway has to bring him out of class due to a nosebleed. They become friends at the end of the book.