He rang up Scotland Yard, asking for certain arrangements to be made, with the result that by the time he and Constable Caldwell reached the great building, two plain clothes men were waiting for them, one of whom handed French a small handbag and a warrant for the arrest of Mrs. Vane, alias Mrs. Ward, alias Mrs. Root of Pittsburg, U. S. A. Then the four officers squeezing into the taxi, they set off for St. John’s Wood Road. Big Ben was striking half-past nine as they turned into Whitehall. The night was fine, but there was no moon, and outside the radius of the street lamps it was pitchy dark. The four men sat in silence after French had in a few words explained their errand to the newcomers. He and Caldwell were both in a state of suppressed excitement, French owing to the hope of an early solution of his difficulties, the constable to the possibilities of promotion which a successful issue to the expedition might involve. The other two looked upon the matter as a mere extra job of work, and showed a lamentable lack of interest in the proceedings. They pulled up at St. John’s Wood Road, and dismissing the taxi, followed Constable Caldwell to the gate of a carriage drive which there pierced the high stone wall separating the houses from the street. On the upper bar of the gate were the words, “Crewe Lodge.” To the right hand was a wicket gate, but both it and the larger one were closed. Inside the wall was a thick belt of trees through which the drive curved back, and, lit up through the interstices of the branches by the street lamps, the walls and gable of a small house showed dimly beyond. No light was visible from the windows, and, after a moment’s hesitation, French opened the wicket gate and all four entered. “Wait here among the trees, Pye and Frankland,” he whispered. “Caldwell, you come on with me.” The drive was short, not more than forty yards long, and the complete outline of the house was speedily revealed. It seemed even smaller than the first glance had shown, but was charmingly designed, with a broken-up roof, large bow windows, and a tiny loggia into which opened a glass panelled door. To be so near the centre of a great city, it was extraordinarily secluded, the trees and wall, together with some clumps of evergreen shrubs, cutting off all view of the road and the neighbouring houses. The front of the house was in complete darkness, and instinctively treading stealthily, the two men moved round to the side. Here also there was no light, and they pushed slowly on until they had completed the circuit and once more reached the front door. “Looks as if the place is empty,” French whispered as he pressed the electric bell. There was no response to his repeated rings. The house remained dark and silent. French turned again to the constable.