"On this occasion, however, he discovered that they made four," replied the major, dryly. "Well, the man and the woman put the body into the carriage--a closed carriage, I suppose?" "Yes," assented Arkel, with a nod, "a brougham." "A doctor's brougham?" "What," cried the inspector, with a look of surprise, "has the scamp told you?" "He has told me nothing. Please go on." "Well," said Arkel, making his invariable beginning, "when the body was placed in the carriage and the door closed, the woman went away." "In what direction?" "She returned through your grounds, but where she went Battersea does not know." "I do, however," muttered Jen, divining that Dido had taken the usual route back to "The Wigwam." "And the man?" "He mounted the carriage-box and drove off. It appears that there was no coachman." "I don't wonder at that," rejoined the major. "This precious pair were afraid to trust their infernal secret to a third party. No doubt the horse, being quiet, was left to stand in the deep shadow of the lane, while the robbers stole the corpse. However, I understand. The woman went away, the man mounted the box, and I suppose, drove off with the corpse." "Also with Battersea," added Arkel, with a significant smile. "It seems that the tramp wished to see the end of this singular adventure, or, no doubt, he wished to make money out of it." "By blackmailing? I see. I suppose he hung on behind." "Yes; like a street arab. He was one, once, you know, major, and has not forgotten his early habits. Well, he was driven with the carriage to Deanminster." "Quite so, and into that gloomy courtyard which surrounds the house of Dr. Etwald," added Major Jen, with a satisfied smile, "Battersea saw the doctor take the body out of the carriage and carry it into the house. Then, on his return--Etwald's I mean--he unharnessed the horse and put it into the stable; also the carriage into the coach-house. Is that not so, Mr. Arkel?" "Battersea told you," stammered Arkel, amazed at his insight. "I assure you he told me nothing. But I am as clever as Battersea, and can put two and two together. Next day Battersea went to Etwald, did he not, and tried to blackmail him, but this clever doctor compelled him to keep silent." "It's all quite true," assented the inspector, thunderstruck; "though how you guessed it all I cannot say. But, as you know so much, perhaps you can tell me one thing more, which bothers me not a little. How did Dr. Etwald compel Battersea to keep silence?" "Very easily," said Jen, with a shrug. "Battersea is half negro. The black race adore the Voodoo stone, of which Dr. Etwald is the possessor. Etwald simply threatened Battersea with the vengeance of the Voodoo stone if he spoke. Therefore, he held his tongue, and was forced to confess all this only by your threatening to have him arrested as the murderer of Mr. Alymer. "I did threaten him; but how you know--"