Caroline Tate and her friend Stacy Baurichter learn that sometimes it is better to talk to people directly after their experiences spying on the mysterious man upstairs and becoming convinced he is a killer who is after Caroline and her brother. Caroline is a big fan of paleontology. She regularly visits the nearby New York Museum of Natural History, where her “very best adult friend” and paleontologist, the colorblind Mr. Gregor Karetsky, talks with her whenever she comes. Her brother, JP, is 13 years old, annoying (to Caroline, at least), and way into electronic experiments gone wrong more often than right. Her mother is divorced, sometimes threatens to send them off to their father in St. Louis when they misbehave, has unsuccessfully been searching for a boyfriend / husband #2, and is sporadically telling Caroline the (always numbered) things she loves about her. Stacy is Caroline's best friend her own age, and she wants to be an investigative journalist when she grows up.
Stacy and Caroline decide to do an investigative research project for school, and decide on neighbors to research. Caroline finds a letter in the trash to her new upstairs neighbor Frederick Fiske saying that the lady is good, and to get rid of the kids before May 1st. Along with it, she finds an overdue library notice about a toxicology book – basically, as she finds out shortly after, a book on poison. She and Stacy draw the conclusion that the letter is talking about her, JP, and their mother.
As she and Stacy are discussing, Stacy calls up an investigative journalist and asks about his techniques for finding out information about his subject. Stacy is miffed when the journalist not only guesses how young she is, but also tells her that he simply called up the subject and asked for an interview. How boring, Stacy thinks! Caroline recognizes her friend might be mixing up detective work and journalism, and that the journalist was right. Neither think it's an appropriate course of action with a potential murderer, however.
During a sleepover, Stacy's parents respond to Stacy's comments about her “people” research within her own building, they realize that their parents know a lot about the people they are looking for information about. Stacy's parents have met them. The reader realizes that the investigative journalist is being proven correct.
Later at the natural history museum, when Caroline talks to Mr. Karetsky, he doesn't think Mr. Fiske is a murderer. Caroline can't quite believe it, so when her mother decides to go on a date with Mr. Fiske, she's freaked out. On their date, Caroline tells JP and he goes up (with his photographic memory) to search for evidence. He brings back several envelopes with several items that they imagine to be evidence with their colored vision of his intentions, but that to the reader, are clearly innocuous. The worst is a dead rat, retrieved in response to a Latin term from Stacy which neither sibling recognizes. JP does know that corpus means body, however – thus the dead rat. They stuff the evidence into a pair of galoshes from a former date of their mother's that she always forgets to give to goodwill. The sugary treats from Mr. Fiske (which the siblings imagine to be sprinkled in arsenic as opposed to sugar) meet the same fate.
After Caroline and Stacy have an argument, Caroline asks to invite her friend over for dinner to make up. She also invites Mr. Karetsky. She finds out the day of that her mother (who likes Mr. Fiske quite a bit) has decided to invite him over, too. Caroline and JP (and Stacy) are not pleased, but hide it and form a plan. But things don't go according to plan. At dessert, after Stacy pours milk on his shoes to induce them to take them off and get rid of their electricity-blocking rubber soles, JP manages to short-circuit the entire building instead of shocking and incapacitating Mr. Fiske and catching him red-handed. While the lights are out, each tells their story. Mr. Fiske, it turns out, is a medieval history professor who is writing a popular fiction book. His book has a May 1st deadline, and he has been having trouble bringing the kids in his book to life, so his editor has told him to cut them. He isn't a murderer after all. The lights come on, and it's clear that Mr. Fiske and Caroline's mom like each other – they are holding hands. By JP and Stacy's embarrassment, it looks like they were probably holding hands, too.
Best part of story, including ending:
Caroline and Stacy, like most pre-teens, have their own viewpoint and ideas about things, but also like most pre-teens, don't always believe or want to talk directly about the things that are bothering them.
Best scene in story:
I don't have a favorite scene per say, but I think Mr. Karetsky is a great character. He is thoughtful and a good mentor to Caroline, getting to know her and her interests at the museums and sharing a bit about himself. He knows her well enough (including her scientific interests) that he is able to give her a wonderful gift when she invites him along with Stacy to dinner - a dinosaur bone.
Opinion about the main character:
Caroline and Stacy try to figure things out on their own, but are sometimes misguided. It takes them a while to figure out that you should really talk to people and find out their side of the story.