Carter is a fourteen-year-old boy who travels the world with his archaeologist father. He dresses professionally in button-down shirts and loafers, a habit instilled by his father to help him present well to others. Having spent most of his life in airports and dig sites, he possesses extensive knowledge of ancient history but lacks a traditional home. He steps reluctantly into a magical conflict following an accident at the British Museum.

Sadie is a young girl raised by her maternal grandparents in England following her mother's death. She wears combat boots and dyes streaks of her hair red to preemptively give people a reason to stare at her. Unlike her cautious brother, she acts impulsively and speaks her mind directly. She discovers a natural aptitude for reading ancient hieroglyphs and casting spells.

Bast is the Egyptian goddess of cats who serves as a dedicated protector to the Kane children. She can appear as a small pet cat named Muffin or take human form as a lithe warrior wielding twin knives. She fulfills a promise made to the Kane parents years ago to watch over their family.

Set is the Egyptian god of chaos, newly released from an ancient imprisonment. He manifests with dual faces—one of a cruel human and one of a vicious beast. He seeks to build a massive pyramid in the desert to amplify his powers and unleash destruction upon the modern world.

Amos is Julius's brother and a powerful magician based in Brooklyn. He takes custody of Carter and Sadie after their father disappears, bringing them to his heavily warded mansion. He provides the siblings with their first real introduction to the world of Egyptian magic and their family's heritage.

Julius is an archaeologist specializing in ancient Egypt and a secret descendant of pharaohs. He has spent years on the run from the House of Life, traveling with his son. Convinced he must take drastic action to prevent a global catastrophe, he orchestrates a dangerous magical ritual at the Rosetta Stone.

Zia is a highly trained magician belonging to the worldwide organization known as the House of Life. She commands formidable fire magic and wields a lion-headed staff. Raised within the strict traditions of her order, she initially views the Kane siblings as dangerous lawbreakers but eventually offers them crucial guidance.

Desjardins is a senior magician within the House of Life. He rigidly adheres to the ancient laws forbidding magicians from allying with gods. He views the Kane family as a severe threat to global order and actively hunts the siblings across the globe.

Iskandar is the ancient and wise Chief Lector of the House of Life. He oversees all magicians globally and possesses an incredibly long memory spanning centuries. Though bound by the strict laws of his organization, he shows a willingness to listen to the Kane siblings.

Ruby was a diviner and the mother of Carter and Sadie. She died under mysterious circumstances at Cleopatra's Needle in London when her children were very young. Her foresight regarding a coming magical imbalance set her family on their current path.

Anubis is the Egyptian god of funerals and the guide for souls entering the afterlife. He oversees the Hall of Judgment and the scales of truth. He feels isolated due to his grim duties and questions Sadie to determine if she is worthy of his assistance.

Khufu is a magical baboon living with Amos in New York. He strictly eats foods that end in "O" and communicates through grunts that Carter and Sadie gradually learn to interpret. He fiercely defends the Kane family when their home is attacked.

Thoth is the Egyptian god of wisdom and knowledge. He adapts heavily to modern American culture, spending his time eating barbecue and playing music. He challenges Carter and Sadie to prove their independence before offering them magical knowledge.

Doughboy is a small wax shabti, an enchanted magical servant created by Julius Kane. He lacks feet to prevent him from running away. He grudgingly answers questions and retrieves information for the Kane siblings.

Nut is the Egyptian goddess of the sky. She reaches out to Sadie to offer guidance, explaining the complex history of her godly children. She tasks Sadie with delivering a message to her estranged husband.

Horus is the Egyptian falcon god of war and the sky. He seeks to reclaim the throne of the gods from Set. He pushes Carter toward aggression and leadership, demanding the boy claim power to restore order to the divine hierarchy.

Isis is the Egyptian goddess of magic. She is a highly strategic deity who tries to exert control over Sadie's actions. She provides immense magical strength but frequently clashes with Sadie's independent nature.