Eleven-year-old Timmi Lafler used to write letters to Grampy Lafler, her only surviving grandparent, but she gave up years ago because he never replied. But now her father wants the family all to spend two weeks of the summer in Grampy's isolated cabin in the woods in Maine. At first Timmi doesn't want to be there - she's missing important baseball games back at home in Scranton, Pennsylvania, and she's sick of Grampy acting like an affectionate grandfather after ghosting her for six years. But Timmi feels like there's some dark secret explaining why Dad and Grampy don't get along, and resolves to find out.
Grass and Sky contains examples of:
- Affectionate Nickname: Grampy addresses Timmi's little sister Rebecca as "Blue Eyes," which makes Timmi wonder if that makes her Brown Eyes.
- Annoying Younger Sibling: Timmi thinks Rebecca is an annoying brat, and their parents are way too indulgent of her.
- Baby's First Words: According to Grampy, Timmi's dad's first word was "Dada."
- Bad People Abuse Animals: While Timmi and Rebecca are in the rowboat, they see three drunks camping illegally on Blueberry Island chase a moose across the lake in their motorboat. They yell at the men to stop, but they just laugh until Grampy cuts them off in his boat. Later, Grampy tells the girls a story about the men chasing a deer in a car until it had a heart attack and died.
- "Be Quiet!" Nudge: During one of Grampy's stories, Timmi makes fun of his accent. Mom flicks her arm with her foot, but Grampy doesn't notice.
- Class Reunion: Timmi's parents go to her dad's twenty-five-year reunion in the town of Dexter, in which he will be inducted into the local sports hall of fame, leaving Timmi and Rebecca alone with Grampy.
- Dead Guy Junior: Timmi was named after her grandmother.
- Founding Day: Grampy hates the Fourth of July because that's when the people who camp by the lake get drunk and rowdy and start making trouble for everyone else.
- I Never Got Any Letters: Timmi finds three letters Grampy wrote to her years ago, all stamped NOT ACCEPTED AT THIS ADDRESS. She realizes her parents sent them back and didn't tell her about them because they wanted to keep Grampy away from her.
- "Kiss the Cook" Apron: The trespassers show up to the baseball game in these aprons.
- Only Known by Their Nickname: Timmi hates being called by her full first name, Timothea.
- Proof Dare: Grampy threatens to report the trespassers. One of them says, "It's your word against ours, old man. You can't prove nothing."
- Recovered Addict: Grampy used to be an alcoholic. He used to be friends with the three trespassers, and behaved just as badly as them if not worse. Timmi's father spent his childhood in constant fear of Grampy's next bout of drinking. The final straw was after Rebecca was born, when Grampy went to the hospital demanding to hold her. He tried to grab her out of the bassinet and almost dropped her while fighting with the nurses. After that, her parents decided that Grampy wasn't safe and cut him out of their life. Grampy sobered up and started attending Alcoholics Anonymous meetings after that, but it was too late for his family.
- Shoo the Dog: Timmi's family used to have a beagle named Charlie, but Rebecca was allergic to him, so they sent him to live with Grampy. He's elderly, but still alive when they visit.
- Tall Tale: Grampy is fond of telling exaggerated stories about his family history, at one point claiming that Paul Bunyan stole the credit for his great-great-grandfather's work.
- Trivial Title: "Grass and sky" is how Timmi refers to a difficult jigsaw puzzle Grampy owns that features grass and sky with only a thin strip of ocean.
- Vanity License Plate: Grampy's jeep has a license plate that says "GOFISH."
