Short of an airship, he could conceive no device whereby the missing six could have made their silent departure. He was shaken out of his stupor by Haredale. "Pull yourself together, Mr. Alden," cried the latter. "Can't we _do_ something? Here's half Scotland Yard in the place and nobody with an intelligent proposal to offer." Mr. Alden shook himself, like a heavy sleeper awakened. "Where's Miss Oppner?" he jerked. Haredale started. "I don't know," was his reply; "but I can go and see." He forced his way past the knot of people at the door, ignoring Inspector Sheffield, who sought to detain him. Rapidly he ran through the rooms composing the suite. In one he met Zoe's maid, wringing her hands with extravagant emotion. "Where is your mistress?" "She has gone out, m'sieur. I cannot tell where. I do not know." Haredale's heart gave a leap--and seemed to pause. He ran to the stairs, not waiting for the overworked lift, and down into the hall. "Has Miss Oppner gone out?" he demanded of the porter. "Two minutes ago, sir." "In her car?" "No, sir. It was not ready. In a cab." "Did you hear her directions?" "No, sir. But the boy will know." The boy was found. "Where was Miss Oppner going, boy?" rapped Haredale. "Eccleston Square, sir," was the prompt reply. The Marquess of Evershed's. Then his suspicions had not been unfounded. He saw, in a flash of inspiration, the truth. Zoe Oppner had seen in this disappearance the hand of Severac Bablon--if, indeed, if she did not _know_ it for his work. She was anxious about her father. She wished to appeal to Severac Bablon upon his behalf. And she had gone--not direct to the man--but to Eccleston Square. Why? Clearly because it was Lady Mary, and not herself, who had influence with him. Hatless, Haredale ran out into the courtyard. Rohscheimer's car was waiting, and he leapt in, his grey eyes feverish. "Lord Evershed's," he called to the man; "Eccleston Square." CHAPTER XXI A CORNER IN MILLIONAIRES At the moment that Julius Rohscheimer's car turned into the Square, a girl, enveloped in a dark opera wrap, but whose fair hair gleamed as she passed the open door, came alone, out of Lord Evershed's house, and entering a waiting taxi-cab, was driven away. "Stop!" ordered Haredale hoarsely through the tube. The big car pulled up as the cab passed around on the other side. "Follow that cab." With which the pursuit commenced. And Haredale found himself trembling, so violent was the war of emotions that waged within him. His deductions were proving painfully correct. Through Mayfair and St. John's Wood the cab led the way; finally into Finchley Road. Fifty yards behind, Haredale stopped the car as the cab drew up before a gate set in a high wall. Lady Mary stepped out, opened the gate, and disappeared within. Heedless of the taxi-driver's curious stare, Haredale, a conspicuous figure in evening dress, with no overcoat and no hat, entered almost immediately afterwards.