This book concerns a teenager, Susan, who is moving back to Boston with her family after having lived in New York for several years. When she gets back, she finds her long-time best friend Colleen acting strangely. Colleen is too thin and jumpy, and she is fixated on a death which everyone believes was a drug overdose, but that Colleen insists was murder.
When Susan arrives for her first day of school, a crowd is gathering outside the building. Colleen has been found dead--also apparently of a drug overdose. Everyone believes this to be true, citing her recent strange behavior and appearance. Susan, however, believes that Colleen was killed because of her knowledge about the previous muder and decides to use the fact that no one at the school (other than her boyfriend, Patrick) knows she and Colleen were friends to try to find the murderer.
Because both deaths appear to be drug overdoses, Susan decides to make connections with drug dealers in the school. She assumes a cynical persona--a girl from New York who is unhappy about her move to Boston and is trying to find a drug dealer. Because of this sudden change in personality, she alienates her boyfriend, her parents, and her teachers, but she is quickly befriended by Tim Connors, a student who appears to be completely clean-cut. He is popular, attractive, and an athlete. No one at school knows that he is a drug dealer, but he is--probably the biggest drug dealer in the school.
Susan begins to date Tim as part of her investigation, and is regularly invited to attend afternoon drug parties at Tim's house with Tim and his friends. One in particular--Beverly, Tim's ex-girlfriend--seems to be trying to tell Susan something, but Susan is never sure what it is. Patrick becomes increasingly suspicious of Susan's behavior, particularly when Susan tries to keep him out of the way of her investigation by convincing him that she knew about Colleen's drug problem all along. As Susan's comments to Tim about Colleen's death become more pointed and Patrick starts asking questions, too, the danger mounts.
Patrick is pushed down the stairs at school, presumably by Tim, resulting in several broken bones. Susan goes to the hospital to visit him, but decides she must go to Tim's house, where she knows he and his friends will be having their usual afternoon party, to get proof that Tim killed Colleen.
However, at the same time, Beverly--who also knows that Tim must have pushed Patrick down the stairs--comes across an old yearbook with a picture of Susan and Colleen in it. She knows that they must have been friends, and that Susan is not what she appears to be. She knows that Susan will be in danger, so she goes to Tim's house as well, to try to protect Susan and also to let Tim know that he can't continue to get away with the drug dealing and killing.
When she gets to Tim's house and shows him the yearbook, he becomes consumed with rage and decides to kill Susan, threatening to kill Beverly. At first, Beverly is too afraid to do anything, watching while Tim beats Susan and prepares to give her a lethal drug overdose as well. Finally she gathers her courage and calls the police.
This report prepared by Heather B.