An elderly ex-serviceman and widower looks to avenge his best friend's murder by doling out his own form of justice.

Andrew Crocker-Harris has been forced from his position as the classics master at an English public school due to poor health. As he winds up his final term, he discovers not only that his wife, Millie, has been unfaithful to him with one of his fellow schoolmasters, but that the school's students and faculty have long disdained him. However, an unexpected act of kindness causes Crocker-Harris to re-evaluate his life's work.