The Kingdom is a historical fiction revenge drama set in Co Kerry, Ireland, after the Great Famine.The film focuses on Queen Victoria's visit to Killarney in 1861. A young actress returns from America to discover her family has suffered due to the local gentry. As the wealthy residents of Muckross House prepare for the royal visit, Ciara seeks revenge. She uses her acting talent to become a Lady’s Maid in the ruling family. Amidst the chaos of hiring new staff and making renovations to impress the Queen, Ciara finds ways to disrupt the visit, aiming for financial ruin left in the Queen's wake. She also gathers support from unhappy servants.

When she learns that a grand stag hunt will highlight the Queen’s visit, she plans to sabotage it, thinking it will harm the Herbert family's reputation and finances. However, Ciara starts to see a different side of the gentry, discovering the Herbert family’s well-known efforts to help during the famine, including providing seeds, planting techniques, food, and funds. She also finds out that the Queen had invested in famine relief and was horrified by the suffering in Ireland. Could she have misjudged the Herberts and who was truly to blame for her family's troubles? As she confronts these questions, events spiral out of her control. With the hunt approaching, Ciara uncovers a darker plot: an assassination attempt on the Queen, intended to frame her for the crime.

Ciara is shocked that her actions could lead to murder. She must now decide whether to save the Queen or the people she seeks revenge against. Although she hates violence and fears execution, she faces a new choice after saving the Queen. Should she continue pretending to be a loyal Lady’s Maid, celebrated as a hero, or should she push for justice for her people, risking her safety? In a world where her people are oppressed, can kindness really ease her guilt? Or is her involvement too deeply ingrained, as her friend Stephen suggests? She may have been wrong about the gentry's direct role in her family's fate, but was she wrong about their guilt?