Hercules is a twelve-year-old seventh-grader grieving the loss of his parents, who died a year prior in an accident. He lives with his older brother on their family property, Beal Brothers Farm and Nursery, in Truro, Massachusetts. Physically small despite his mythical namesake, he relies on sarcasm and humor to mask his emotional pain. He receives a unique school assignment to recreate the twelve labors of Hercules in a modern context.

Achilles is Hercules's older brother and the current manager of Beal Brothers Farm and Nursery. He previously worked as a writer for publications like Smithsonian Magazine and National Geographic, traveling the world before returning to Truro. He handles the practical demands of the business while acting as the primary caretaker for his younger brother.

Lieutenant Colonel Hupfer is a retired marine and strict humanities teacher at the Cape Cod Academy for Environmental Sciences. He assigns the Classical Mythology Application Project and demands high standards, regular memorization, and rigorous discipline from his seventh-grade class. Behind his intimidating exterior, he quietly pays attention to his students' personal struggles.

Viola is Achilles's girlfriend who frequently spends time at the Beal property. Hercules views her with suspicion early on, assigning her supernatural traits to justify his emotional distance. She is highly perceptive and recognizes that the Beal brothers struggle to communicate their feelings.

Mindy is a stray dog that Hercules adopts shortly after his parents' deaths. She serves as his constant companion, accompanying him to the Dune every morning to watch the sunrise. At the family nursery, she acts as a gentle greeter for customers, showing a natural ability to put anxious people at ease.

Pirate Cat is a heavily scarred, one-eyed feline that initially terrifies Hercules. Originally part of a feral group, she reveals a surprisingly affectionate nature when separated from the pack.

Elly is Hercules's best friend who attends the local Truro Middle School rather than the Academy. She frequently spends time with him after school and encourages him when he feels overwhelmed by his mythology assignment.

Henry is a student at the Cape Cod Academy for Environmental Sciences. He is quick to ask incessant questions in class, particularly regarding his teacher's military background. He eagerly participates in Hercules's early community tasks.

Ty is a student at the Academy who has a history of teasing Hercules about his stature. He shares classes with Hercules and occasionally helps with the manual labor assignments at the Beal family business, maintaining a tense but evolving dynamic with his classmate.

Mr. Neal is a neighbor of the Beal family in Truro. He proves helpful during an animal encounter and lives nearby with his wife in a house vulnerable to severe coastal weather patterns.

Mrs. Neal is a Truro resident who lives in a coastal home near the Beal farm. Her residence puts her at risk during the intense storms that frequently batter the Cape Cod area.

Mrs. Savage is an older neighbor of the Beals who creates and displays animal sculptures in her yard. She pays close attention to how light affects her art and shares this philosophical view with Hercules.

Mr. Moby is a school bus driver who recently moved into the house next to the Beals. He initially presents a grouchy exterior, threatening neighbors over minor lawn care issues, though he shows a softer side when dealing with animals.

Dr. S. Klatt is the principal of the Cape Cod Academy for Environmental Sciences. She manages the school's response to student misconduct and handles logistical emergencies caused by severe weather on the Cape.

Mr. Farley is the custodian at the Cape Cod Academy for Environmental Sciences. Having previously worked at Truro Middle School, he is familiar with the Beal family history and offers quiet encouragement to the incoming seventh-grader.

Mrs. DeJong is the biodiversity teacher at the Academy. Her rigorous science assignments inadvertently provide Hercules with the framework for completing his mythology project.

Mrs. Bontemps is a neighbor of the Beal family who has extensive connections within the local community. She possesses the organizational skills to quickly mobilize groups of retired teachers when physical assistance is needed.