England, 1872. The night before he is to be hanged for a murder he did not commit, young Dr. Gordon Ramsey is visited in his cell by his old mentor, eminent surgeon Sir Joel Cadmund. Cadmund offers to see that Ramsey gets a proper burial and gives him a sleeping powder to get him through the night, which Ramsey takes, unaware it is really an East Indian drug, "nind andhera" ("the black sleep"), which induces a deathlike state of anesthesia. Pronounced dead in his cell, he is turned over to Cadmund, who promptly revives him and takes him to his home in a remote abbey. Cadmund explains he believes Ramsey is innocent and needs his talents to help him in an project, which he is reluctant to immediately discuss further.