Mark Easterbrook is a professional historian who finds that he has been unwittingly drawn into a complex scheme of murder when he witnesses a fight inside a café and comes to discover something nefarious about a local historical inn called the Pale Horse. Mark is a down-to-earth man of good character who cannot help but try to set things right when he has the power to do so.

Mark could have stopped asking questions and walked away, but he feels a strong sense of justice that he must act upon due to his unique knowledge of the situation. There is nobody else who cares to set things right, and so he feels that he must act, even demonstrating a willingness to leave behind friendships to do so. In the end, Mark leaves Hermia behind, although he had for some time imagined marrying her, and falls in love with Ginger as he realizes that Hermia is not a good fit for his personality while Ginger proves to be an equal partner.

Mark shows that he is both intelligent and resourceful, piecing together the clues of the mystery that continue to elude many others, even drawing on prior knowledge and scholarship in his recognition of the symptoms of thallium poisoning, leading to the case’s solution.