Calvin Becker's family are good Bible-believing missionaries; it's their duty to spread the Word to everyone they meet. But now they face their greatest spiritual challenge right in their own home- Grandma. Foulmouthed, foul-tempered, and heathen through and through, she's staying in the spare room, recuperating from a broken hip-and making it next to impossible for the Beckers to do the Lord's work.

Calvin's pious mom is determined to save Grandma's soul, even if she's doing it through gritted teeth. His father's spending more and more time in his room, blasting opera records to drown out the old lady's voice. And Calvin wishes things would just get back to normal so he could go on vacation and see his beloved Jennifer.

But now Calvin's starting to understand Grandma a little better-and appreciate her a little more. After all, misery loves company.