In the Spider's Web is set in Ash Meadow, a prison for children in Washington State. The story centers on Caitlin Weber, a girl who, in collusion with her mother and four other children, murdered her mother's employer. While the murder is briefly depicted, it is with what happens afterward to two of the perpetrators, particularly Caitlin, that the story is primarily focused.

Arrested less than a week following the murder, Caitlin and her best friend, Sonia, are charged as adults and each sentenced to 22 years in prison. Caitlin was 13 years old; Sonia was 14 years and one week old. Neither had been in legal trouble before. Upon sentencing, they were sent to Ash Meadow where they would stay until they turned 18. Then they would be transferred to Purdy, a prison for adult women, to serve the remainder of their sentences. In the Spider's Web focuses on Caitlin's experience in Ash Meadow and on her relationship with Jerry, her rehabilitation counselor (and the author of this book). Part I of the book provides the reader with a feel for the prison environment that awaits Caitlin, and introduces the reader to the staff and inmates of the Maximum Security unit where Caitlin will live for most of her time in Ash Meadow. Part I also introduces the reader to the relationships between staff, and between staff and the administrators who govern the prison, which relationships will have an effect on Caitlin.

Part II begins with Caitlin's arrival at the prison and the start of her relationship with Jerry. The relationship is rocky at first, because Jerry has the same name and is around the same age as the man Caitlin helped to kill. Although Jerry does not know this at first, Caitlin is effectively haunted by her victim. She is assailed by guilt over what she did, and anger toward her mother whose idea the murder was. She struggles with depression and has contemplated suicide. She wants t deny responsibility for her role in the murder and resents Jerry