A 60-year-old retired assassin who formerly worked for the clandestine agency known as the Museum. She relies heavily on her physical training and hand-to-hand combat skills to complete missions. Abandoned by her mother early in life, she maintains a fierce independence. She organizes her all-female squad, Project Sphinx, and takes charge when their retirement cruise is interrupted by a lethal threat.

An aristocratic assassin from a family with a legacy of government espionage. As the daughter of an OSS member, she specializes in firearms and acts as the detail-oriented planner for Project Sphinx. She struggles with the deep grief of recent widowhood, appearing frail to outsiders while maintaining her lethal accuracy.

A breast cancer survivor and poison expert for Project Sphinx. She distills rare and untraceable toxins for the agency. Driven by the loss of family members in the Vietnam War, she views her lethal profession as a method to right historical wrongs. She hides her occupation from her wife by pretending to be an accountant.

An uninhibited explosives and weaponry expert for Project Sphinx. The descendant of Russian Jewish radicals and Dutch resistance fighters, she embraces her heritage and utilizes her romantic history to gather intelligence. She approaches her deadly work with practical energy and a preference for heavy firearms.

A founding member of the Museum and former British intelligence operative. Codenamed Shepherdess, she survived a concentration camp during World War II and previously served in an all-female squad called the Furies. She acts as a strict instructor to the Project Sphinx team, teaching them to weaponize their traditional femininity.

A seasoned agent in the Museum who initially acts as a supervisor for the young Sphinx team. He holds deeply sexist views, routinely treating his female colleagues as subordinates or objects. He harbors a massive ego and deeply resents situations where female agents prove themselves capable.

A mild-mannered curator who acts as the second-in-command for the Museum's Acquisitions department. His primary responsibility involves outfitting the assassination squads with the necessary equipment for their missions. The Project Sphinx members view him with fondness and consider him a harmless contact.

The brisk, highly skilled deputy head of the Museum's Provenance department, which handles research and target identification. She is pregnant and on medical leave. Possessing a deep background in art history, she communicates cryptically with field agents regarding internal agency politics.

A British assassin who works for the Museum. He desires a traditional domestic life with a marriage and children, conflicting with the demands of his profession. He acts as a capable agent who genuinely respects women as his equals.

A young Ukrainian app developer and computer expert. She serves as Billie's protégé and provides technical support for the team, utilizing her coding skills to create secure communication channels disguised as menstruation tracking apps.

Mary Alice's devoted wife who plays softball and enjoys a quiet domestic routine. She operates under the assumption that her wife works as an accountant, initially unaware of the lethal reality of her spouse's career.

A retired Museum colleague who works alongside the Project Sphinx team in their early years. He smokes regularly and aligns himself with the male-dominated culture of the agency's older generation.

A former SOE member and Constance's brother. He acts as a recruiter for the Museum, seeking out women with combat skills and moral flexibility to join his sister's experimental new squad.

The head of the Museum's Acquisitions department. He acts as a cheerful but unwanted supervisor on early missions, expressing a strong preference for luxury travel and Swiss spas.

An ambitious Museum agent who joined the agency as a teenager after killing the wealthy employers who overworked his parents. He values financial gain and dreams of purchasing a specific Parisian townhouse.