Frances “Frankie” McGrath is a 20-year-old nursing student raised in privilege in Coronado, California. Eager to find purpose beyond the socialite life expected of her, she is inspired to become a combat nurse. Frankie is initially naïve and bound by strict rules, but her deep love for her brother drives her to enlist in the Army Nurse Corps.

Rye Walsh is Finley McGrath's friend and an active-duty military pilot. Unlike the traditional men in Frankie's family, he recognizes her intelligence and suggests she has the potential to be a hero. He is a competent, respected captain who provides a living connection to Frankie's beloved brother while stationed overseas.

Ethel is a seasoned nurse serving in Vietnam who becomes one of Frankie's roommates. Having already experienced the harsh realities of the evacuation hospital, she initially acts as a foil to the naïve Frankie. She copes with the daily trauma of the wards by making jokes, dancing, and providing steadfast support to her fellow medical staff.

Barbara, known as Barb, is an experienced nurse who shares a small hut with Frankie and Ethel. Blunt and practical, she helps the new arrivals adjust to the overwhelming nature of mass casualties. Despite her tough exterior, she is fiercely loyal and becomes a vital confidante for the younger nurses.

Henry Acevedo is a psychiatrist and widower who crosses paths with Frankie stateside. Having lost his wife to cancer, he carries his own grief while opposing the war as a concerned uncle. Warm and respectful, his medical background makes him uniquely equipped to understand the invisible wounds carried by returning medical personnel.

Finley is Frankie's beloved older brother who has recently graduated from the Naval Academy. He is lauded by their traditional parents, who proudly display the military men of their family on a dedicated wall in their home. His deployment to Vietnam serves as the initial catalyst for Frankie's own enlistment.

Mr. McGrath is a wealthy patriarch who takes immense pride in his family's history of military service. He maintains a wall of photographs dedicated to male ancestors who served in combat. While he celebrates his son's military career, he strongly disapproves of his daughter's desire to serve, believing women belong in civilian domestic life.

Mrs. McGrath is a wealthy California socialite deeply invested in appearances and high society. She expects Frankie to focus on marriage and country club life rather than a grueling career. Highly concerned with her family's reputation, she avoids discussing unpleasant realities.

Jamie Callahan is a flirtatious surgeon stationed at the evacuation hospital in Vietnam. He recognizes Frankie's potential as a fast learner and urges her to transfer to the operating room. He frequently relies on alcohol and socializing to cope with the immense stress of his medical duties.

Coyote is a helicopter pilot operating near the Cambodian border. He frequently transports personnel and helps organize social events for the medical staff, offering brief moments of levity and escape from the grim realities of the hospital.

Dr. Ted Smith is the presiding doctor in the neuro ward at the hospital in Saigon. He recognizes Frankie's competence early on, praising her as a fast learner and guiding her through difficult medical procedures in both the hospital and local villages.