Mab is the eldest of the sixteen-year-old Mitchell triplets. She attends Bourne Memorial High in Track A, a designation for academically advanced students. Driven and highly observant, she volunteers at the school's tutoring center and studies for college entrance exams with her friends. She possesses a strong sense of justice regarding the corporate pollution that destroyed her town.

The middle Mitchell triplet serves as Bourne's unofficial librarian after the actual facility closes. She stores the town's massive book collection in her own home and relies on her photographic memory to locate specific texts for residents. Monday prefers yellow objects, clothing, and meals, which provides her with a sense of order and decisive clarity.

The youngest Mitchell triplet possesses a genius-level intellect that easily exceeds her high school curriculum. Born with physical abnormalities and idioglossia, she uses a wheelchair and communicates through a specialized voice app on her tablet. She is highly perceptive and emotionally intelligent, quickly understanding the hidden motives of the adults around her.

Nora is the mother of the triplets and works as Bourne's therapist, bartender, and baker. Widowed when her husband died from cancer caused by the town's contaminated water, she channels her protective instincts into a long-running legal battle against Belsum Chemical. She continuously searches for evidence to prove the corporation knowingly poisoned her community.

River is a new student at Bourne Memorial High who practices amateur magic under the stage name Raging River. Having lived a sheltered life in Boston, he arrives initially ignorant of his family's dark history in the area. His presence causes immediate friction among the student body, though he soon draws the attention of the Mitchell sisters.

Nathan is the son of Belsum's original founder and the current head of the rebranded chemical company. He moves his family into Bourne's former library building, offering jobs to the locals while loudly insisting his new product is perfectly safe. He maintains a polished, agreeable exterior that masks his ruthless business intentions.

Duke is the original owner of Belsum Chemical and the patriarch of the Templeton family. Years ago, he oversaw the factory operations that poisoned Bourne's water supply and subsequently abandoned the town. His legacy of environmental destruction hangs over the current residents.

Operating out of the local church, Pastor Jeff works as Bourne's clergyman and physician. He repurposes his building into a yoga studio and copy center to fill resource gaps in the economically depressed town. He actively discourages the use of stigmatizing labels, teaching his students to focus on their unique strengths.

Omar serves as the mayor of Bourne. He attempts to balance the severe economic depression of the area with the health concerns of his constituents. His political decisions sometimes put him at odds with Nora, though he maintains that he acts in the town's best interest.

Apple is Nathan's wife, a woman from the wealthy Groves family who moves into the repurposed library. Unhappy in her marriage, she begins attending therapy sessions with Nora. She claims to dislike her husband's actions and spends her time searching the town for old family correspondence.

Winnifred, commonly known as Pooh, is a high school student of Korean heritage who uses a wheelchair. She is a close companion to Mab, having formed a bond when Mab volunteered to read to her during a service project.

Petra is Mab's classmate and friend. The two girls study for their college entrance exams together and share a mutual frustration with their assigned high school duties.

Russell is an attorney who originally helped Nora build her environmental lawsuit. He stepped back from active litigation after experiencing personal family fears, but he continues to assist Nora with basic legal document filings.

Tom works as the town handyman. He gathers discarded materials and repurposes them to help various households repair their homes, providing a crucial service for the under-resourced community.

Zacharias is a former line supervisor at the chemical plant who lost part of his leg to bone cancer. He maintains a cheerful presence in Bourne, working at the local convenience store and frequently socializing at the bar.