As the film opens, Jean Donovan [Melissa Gilbert] and Sister Dorothy Kazel [Pamela Bellwood] meet Sisters Maura Clarke [Mary McCusker] and Ita Ford [Mari Gorman] at the El Salvador airport, and the four pile into a van driven by Jean for the trip back to the mission where Jean and Dorothy live and work. Shortly after leaving the airport, the van is stopped by a group of armed soldiers. The women then go missing, and the US Ambassador to El Salvador, Robert White [Mike Farrell], searches for them, repeatedly following leads and clues that point toward a dangerous eventual truth. His investigation is interwoven with intimate flashbacks that trace Jean's life from college to her surprising transformation, offering a window into the person behind the mission.
In Dublin, during a study abroad year, Jean drinks and parties with friends until she is approached by Father Phelan [Martin Sheen], a Catholic priest asking for help with his ministry to the local poor. At first, Jean is skeptical and self-centered, but gradually she becomes drawn to service and justice, finding a new purpose beyond a comfortable, materialistic life. Back home in the United States, she climbs the corporate ladder at a high-paying firm, indulging in expensive toys like a new car and a motorcycle, yet a growing restlessness gnaws at her. A serious relationship with medical student Doug Cable [Peter Horton] adds more color to her life, but she feels a pull toward something more meaningful. When a Catholic lay missionary program invites her to serve, she accepts and heads to El Salvador, joining Dorothy Kazel in the work among the local poor.
Jean's bold, uncompromising stance against injustice soon brings her into sharp conflict with the Salvadoran military, a force that operates with heavy-handed authority in a climate tainted by external political pressure. The atmosphere grows increasingly perilous as a mutual attraction develops between Jean and Armando [Demián Bichir], a young man who is discerning a path toward priesthood. Armando slips into Jean's world at night, and their bond deepens even as they know their romance is complicated by the danger surrounding them. Jean’s charisma and courage inspire many, but they also draw the ire of those who want to keep the status quo intact. The escalating tension is underscored by Archbishop Oscar Romero [René Enríquez], a figure beloved by the people for his outspoken defense of the oppressed, who is eventually assassinated for speaking out against the regime's abuses.
Despite mounting grief and an ever-present threat from Doug—who warns that their relationship could falter if she does not return to the US—Jean cannot abandon her Salvadoran wards and the children she has grown to love. Her fierce dedication to stay with the people she serves becomes a moral test she cannot easily pass. The story crescendos in a brutally stark turn: a military death squad rapes, tortures, and murders Jean along with the three religious sisters she was driving to the mission house. Ambassador White's pursuit of justice for Jean and her companions is impeded by a complex web of noncooperation from both the Salvadoran authorities and, frustratingly, the US government, leaving a chilling question of accountability in the wake of a devastating tragedy.
