The story takes place in England in 1921. The failure experienced in World War I caused a depressing and painful atmosphere to shroud the whole country. Florence (Rebecca Hall) is a counterfeiter. With a strong sense of justice, she regards it as her duty to expose lies and reveal the truth. She does not believe that there are ghosts in the world, only sinister human hearts. In a boys' boarding school, rumors of hauntings are rampant. In people's mouths, the ghost of a boy who died abnormally lingers on the campus all day and refuses to leave. In order to dispel the fears of students and parents, the school commissioned Florence to investigate. Florence quickly started working, and under her shrewdness and strength, the truth of the incident gradually surfaced. Just when she thought the problem had been solved and was ready to leave, an event occurred that was enough to subvert all her beliefs in this life.