December 1921: Being single and a new Chief, Inspector Rutledge gets the short straw and is called upon by Chief Superintendent Markum to go to the Kentish home of a lord who is recovering from an attempt on his life. In bed with a concussion, the man is convinced someone is trying to kill him after he claims he was struck by the hoof of a running horse whose rider never stopped to check on him.

When he gets there, Rutledge learns that he and the lord were both young cavalry officers and graduated from Sandhurst together. As Rutledge's investigation gets underway, he uncovers even more similarities between his life and that of the man he's sent to protect, all of which grows eerily poignant as the Christmas holiday approaches...