The Freeman family--Charles, Laurel, and their daughters, teenage Charlotte and nine-year-old Callie--have been invited to the Toneybee Institute in rural Massachusetts to participate in a research experiment. They will live in an apartment on campus with Charlie, a young chimp abandoned by his mother. The Freemans were selected for the experiment because they know sign language; they are supposed to teach it to Charlie and welcome him as a member of their family. Isolated in their new, nearly all-white community not just by their race but by their strange living situation, the Freemans come undone. And when Charlotte discovers the truth about the Institute's history of questionable studies, the secrets of the past begin to invade the present.