Sammy is a sharp-witted, curious 13-year-old seventh grader managing a complicated living situation. Abandoned by her mother, she secretly resides with her grandmother in a building restricted to senior citizens. She possesses keen observational skills and a mischievous sense of humor, though her impulsive decisions occasionally cause trouble.

Grams is Sammy's loving, elderly grandmother and sole guardian. Living on a fixed income in a government-subsidized Senior Highrise, she constantly worries about Sammy's safety and behavior. She acts fiercely protective of her granddaughter, going to great lengths to hide Sammy from building management and nosy neighbors.

Oscar is an affable community fixture who operates a local ice cream cart. He presents himself as blind and hard of hearing, a demeanor that makes him a seemingly innocuous presence in the neighborhood. His quiet routine makes him a familiar background figure to the local children.

Marissa is Sammy's 13-year-old best friend and steadfast sidekick. Despite coming from a wealthy family and living in an opulent house in East Jasmine, she experiences deep loneliness due to her parents' constant absence. She struggles with nervous habits but remains incredibly loyal to Sammy.

Heather is a manipulative seventh-grade bully with bright red hair and multiple ear piercings. She immediately targets Sammy on the first day of school, mocking her worn shoes and actively trying to ruin her reputation. She constantly seeks attention and uses deceit to turn peers against Sammy.

Officer Borsch is a grouchy police officer assigned to investigate the recent string of neighborhood burglaries. He previously issued Sammy a jaywalking ticket and maintains a highly suspicious, dismissive attitude toward her. He resents interference in his cases and frequently questions Sammy's credibility.

Mrs. Graybill is Grams's extremely nosy elderly neighbor at the Senior Highrise. She suspects that a child is illegally living in the building and constantly searches for evidence to expose the arrangement. Her frequent snooping acts as a persistent threat to Sammy and Grams.

Gina is a resident of the Heavenly Hotel who becomes the victim of a significant theft. She operates a shop called the House of Astrology under the name Madame Nashira, where she creates birth charts and studies the stars.

Lana is Sammy's absent mother who left her daughter with Grams to pursue an acting career in Hollywood. She makes empty promises about returning soon, creating a strained emotional distance between herself and her child.

Hudson Graham is an elderly neighborhood resident who owns a vast personal library and a dachshund named Rommel. He acts as a kindly mentor figure to Sammy, offering a safe haven when she needs to leave the apartment building.

Bill Eckert is Hudson Graham's quiet new renter. He keeps a low profile and actively avoids speaking to people in public, making him an enigmatic presence in the neighborhood.

Mikey is Marissa's eight-year-old younger brother. He frequently wanders off, skips school, and spends his allowance on junk food, requiring Marissa to constantly watch over him to keep him out of trouble.

Mr. Caan is the stern vice principal at William Rose Junior High School. He strictly enforces school rules but often fails to see the full context of student conflicts, quickly punishing physical retaliation while missing the initial verbal harassment.

T.J. is a grouchy clerk who works at the local corner store owned by his father. He carries heavy debt due to bad investments in the commodities market, making him anxious and defensive about his financial situation.

Sergeant Jacobson is Officer Borsch's professional partner on the police force. He assists with the ongoing burglary investigations in the neighborhood.

Brandon is Marissa's high school-aged cousin. He works at the mall and occasionally helps keep an eye on his younger cousins when they visit.