Greta Evans, a young American from Montana, is hired as a nanny by the Heelshires. Upon arriving in their small town in the United Kingdom, the elderly couple show Greta her charge: a porcelain doll named Brahms that they treat like their son. They then close the doors behind them so that they can ask Brahms if he wants Greta as his babysitter. The old couple come out and say that Brahms agreed despite having "rejected" many previous babysitters. Over the next day, the couple coach Greta on taking care of Brahms and their house, leave her a list of rules to follow, then leave for a holiday. The rules include reading to Brahms in a loud, clear voice, playing loud music for him, and putting his food in the freezer if he doesn't eat it. It also includes setting up rat traps outside, to make sure the rats don't get inside the house's walls.