The year is 1869. A brutal triple murder in a remote community in the Scottish Highlands leads to the arrest of a young man by the name of Roderick Macrae. A memoir written by the accused makes it clear that he is guilty, but it falls to the country's finest legal and psychiatric minds to uncover what drove him to commit such merciless acts of violence. Was he mad? Only the persuasive powers of his advocate stand between Macrae and the gallows.