Douglas is a 12-year-old boy living in Green Town, Illinois, who experiences a profound spiritual epiphany about being alive at the start of summer. He possesses an intense enthusiasm for the everyday wonders of his environment. With a keen sense of observation, he meticulously records the events of his season in a journal and depends on his family to process his growing understanding of the world.

Grandpa is the wise, crusty patriarch of the Spaulding family who presides over essential summer rituals in Green Town. He finds genuine joy in traditional tasks like making dandelion wine and listening to the sound of manual lawnmowers. He provides a calming presence and dependable advice to his extended family.

Grandma runs a busy, successful boarding house next door to her daughter's home. She relies on instinct and a chaotic kitchen environment to cook wildly popular, mysterious meals for her boarders and family. Her culinary magic stems entirely from her intuitive, messy process rather than precise recipes.

The Lonely One is an active serial killer responsible for strangling several women in Green Town. He operates as an almost mythological figure in the minds of the townspeople, generating an atmosphere of dread that keeps residents locked indoors at night. He frequently targets victims who walk alone near the shadowy ravine.

Tom is Douglas's energetic ten-year-old younger brother who loves to collect statistics about his daily activities. He tracks everything from the number of peaches he eats to the movies he watches. He views the adults around him as absolute protectors and struggles when he realizes they cannot shield him from every danger.

Mr. Spaulding is the father of Douglas and Tom. He encourages his sons to appreciate the natural world by pointing out the subtle details of their environment. He shares a deep enthusiasm for ordinary things and passes this reverence for life down to his children.

Mrs. Spaulding provides a stable, protective presence for her sons in Green Town. Despite her outward confidence, she harbors serious anxieties about the dangers lurking outside their home. Her moments of vulnerability help her children understand that adults experience fear just like anyone else.

At 90 years old, Great-Grandma is the matriarch of the extended Spaulding family. She actively participates in household chores and passes down a profound love for life's wonders to her descendants. She maintains a calm, accepting attitude toward the natural progression of life and aging.

Colonel Freeleigh is an elderly, frail man with an adventurous past. The neighborhood boys view him as a human "time machine" because of his vivid, firsthand accounts of historical events. He sustains his spirit by sharing these memories with the younger generation and making phone calls to distant friends in Latin America.

Helen Loomis is a 95-year-old resident of Green Town with a lifetime of adventurous memories. She strikes up an unusual, deeply intellectual romance with a young local journalist. She views their connection as a meeting of minds that transcends physical age.

Bill Forrester is a local journalist who boards at the house run by Douglas's grandparents. He attempts to introduce modern conveniences to the household before realizing the value of tradition. He develops a profound emotional connection with an elderly woman through their shared conversations.

John Huff is recognized as the best athlete and most capable boy in Green Town. He knows the names of wild flowers, sings cowboy songs, and commands great admiration from his peers. A sudden change in his family's living situation forces his friends to confront the painful reality of losing a close companion.

Charlie is one of Douglas's close friends and regular companions during summer adventures. He acts as the guide who first introduces the other boys to Colonel Freeleigh, recognizing the old man's value as a storyteller.

Clara is the popular president of the Honeysuckle Ladies Lodge. She possesses a calm demeanor that sharply contrasts with the frantic paranoia of her rival. She maintains her social standing effortlessly, leaving others to guess whether her unbroken string of good luck stems from competence or actual magic.

Elmira is an accident-prone, deeply suspicious 35-year-old woman who desperately wants to be president of the local ladies' lodge. She harbors a fierce paranoia that her rival is a practicing witch responsible for Elmira's constant clumsiness and political failures.

Leo is the town jeweler and an enthusiastic amateur inventor. Prompted by a casual suggestion from Douglas, he obsessively works in his garage to build a "Happiness Machine." He struggles to balance his all-consuming mechanical projects with the emotional needs of his family.

Lena is Leo's practical, grounded wife. She manages the household and their children while Leo isolates himself in the garage. She remains highly skeptical of his mechanical inventions, preferring the genuine, authentic experiences of everyday family life over artificial joys.

Lavinia is an independent, headstrong young woman in Green Town. She attempts to maintain a cavalier attitude regarding the threat of the local serial killer, insisting on going out to the movies despite the danger. Her outward courage masks a deep, growing terror as she walks through the darkened streets.

Francine is Lavinia's highly anxious friend. Unlike Lavinia, she openly expresses her fear of the local murderer and frequently protests their decisions to walk near the dangerous ravine after dark.

Mr. Jonas is a retired businessman who drives a wagon filled with secondhand items, singing original tunes to announce his arrival. He operates an informal barter system where townspeople can take what they need for free. He acts as an unofficial caretaker for the community by providing quiet company to the lonely or sick during hot summer nights.

Mrs. Bentley is a 72-year-old woman who hoards mementos from her past in trunks. She struggles with the disbelief of neighborhood children who refuse to accept that elderly people were ever young. She eventually learns to let go of her physical connection to the past to find peace in the present.

Aunt Rose is a well-meaning but overbearing relative who visits the Spaulding family. She insists on imposing order and logical precision on household systems that already work perfectly. Her interference causes unintended chaos before she is asked to leave.

Miss Fern is an elderly woman who, along with her sister, purchases a small electric runabout called the Green Machine. She enjoys touring the town and maintaining a sense of youthful adventure until a startling accident forces her to reconsider her driving habits.

Miss Roberta is an elderly Green Town resident who shares ownership of a silent electric vehicle with her sister. Together, they navigate the immediate consequences of adopting new technology in their old age.

Mr. Black is the abusive, frequently inebriated manager of the town arcade. He despises the old wax fortune-telling machine because of its maintenance costs, treating the inanimate object with a violent hostility that draws the protective ire of the local boys.