It was an hour later when they pulled up at Matherfield's head-quarters and went in to find him. Matherfield, brought to them after some search, rubbed his hands at sight of them.  
"Come at the right moment!" he exclaimed, "I've got news—of Ambrose!"
 
Matherfield evidently expected his visitors to show deep interest, if not passive enthusiasm, in respect of this announcement, and he stared wonderingly on seeing that their faces showed nothing but gloom and concern.
 
"But you—you look as if you'd had bad news!" he exclaimed. "Something gone wrong?"
 
"I forgot that we might have telephoned you from Riversreade Court," replied Hetherwick, suddenly realising that Matherfield seemed to know nothing of the day's happening. "But I thought the Dorking police would do that. Gone wrong!—yes, and it may have to do with Ambrose—we've heard news that seems to fit in with him. But it's this," he went on to give Matherfield a brief account of the day's events. "There you are!" he concluded. "I've no doubt whatever that Baseverie and Ambrose are in at this—kidnapping in broad daylight. Matherfield, you've got to find them!"
 
Matherfield had listened with close attention to Hetherwick's story, and now he looked from him to Penteney; from Penteney to a printed bill which lay on his desk at his side. "I think I see what all this is about," he remarked, after a pause. "Those chaps think they've got—or they thought they got—Lady Riversreade! To hold for ransom, of course. They took Miss Hannaford because she chanced to be there. What they really kidnapped—and there's more of that done than you gentlemen might think, I can tell you!—was Lady Riversreade's sister. But now, however sisters—twin sisters—may closely resemble each other, there comes a time when difference of identity's bound to come out. By this time—perhaps long before—those men must have discovered that they laid hands on the wrong woman! And the question is—what would they do then?"
 
"It seems to me that the more immediate question is—where are the two women?" exclaimed Hetherwick. "Think of their danger!"
 
"Oh, well, Mr. Hetherwick, I don't suppose they're in any personal danger," answered Matherfield. "They're in the hands of brigands, no doubt, but I don't think there'll be any maltreatment of them—set your mind at rest about that. They don't do that sort of thing nowadays; it's all done politely and with every consideration, I believe. As to where they are? Why, somewhere in London! And there are over seven millions of other people in London, and hundreds upon hundreds of thousands of inhabited houses—a lot of needles in that bundle of hay, gentlemen!"
 
"They've got to be found!" repeated Hetherwick doggedly. "You'll have to set all your machinery to work! This can't——"
 
"Wait a bit, Hetherwick," interrupted Penteney. He turned to Matherfield. "You said you had news of this man Ambrose? What news?"
 
Matherfield tapped the printed bill which lay on his desk.
 
"I had that circulated broadcast this morning," he answered. "And then, of course, the newspapers have helped. Well, not so very long before you came in, I was called to the telephone by a man named Killiner, who told me he was the landlord of the Green Archer Tavern, in Wood Street, Westminster——"
 
"Westminster again!" exclaimed Hetherwick. "That seems to be the centre point!"
 
"And a very good thing to have a centre-point, Mr. Hetherwick," said Matherfield. "When things begin to narrow down, one gets some chance. Well, I was saying—this man rang me up to say that if I'd go down there he thought he could give me some information relative to the bill about the missing man. What he'd got to say, he said, was too long for a telephone talk. I answered that I'd be with him shortly, and I was just setting off when you arrived. Of course, I don't know what he can tell—it may be nothing, it may be something. Perhaps you gentlemen would like to go with me and hear what it is?"
 
"I would, but I mustn't," replied Penteney. "I must go to my office and hear if Lady Riversreade or the local police have had any fresh news. Keep in touch with me, though, Matherfield—let me know what you hear."
 
"I'll go with you," said Hetherwick. "Westminster!" he muttered again, when Penteney had gone. "It looks as if this man Ambrose was known In that district."
 
"Likely!" assented Matherfield. "But you know, Mr. Hetherwick, there are some queer spots in that quarter! People who know the purely ornamental parts of Westminster, such as the Abbey, and the Houses of Parliament, and Victoria Street, and so on, don't know that there are some fine old slums behind 'em! But I'll show you when we get down there. We shall go through one or two savoury slices."
 
He was putting on his overcoat as he spoke, in readiness for setting out, but before he had buttoned it a constable entered with a card.
 
"Wants to see you particularly, and at once," he said. "Waiting outside."
 
"Bring him in—straight!" answered Matherfield. He pushed the card along his desk in Hetherwick's direction. "Lord Morradale!" he exclaimed. "Who's he?"
 
"The man who's engaged to Madame Listorelle," replied Hetherwick, in an undertone. "Hampshire magnate."
 
Matherfield turned expectantly to the open door. A shortish, stoutish person, who looked more like a typical City man, prosperous and satisfied, came hustling in and gave Hetherwick and his companion a sharp, inquiring glance which finally settled on Matherfield.
 
"Mr. Matherfield?" he asked. "Just so! I'm Lord Morradale—oh, of course, I sent in my card—just so! Well, Mr. Matherfield, I've had an extraordinary communication from Lady Riversreade. She telephoned to my house in Hill Street this morning, but I was down in the City, and didn't hear of her message till late this afternoon. She says her sister, Madame Listorelle, has been kidnapped! Kidnapped—preposterous!"
 
"I'm afraid it's neither preposterous nor improbable, my lord," answered Matherfield. "I'm quite sure Madame Listorelle has been kidnapped, and Lady Riversreade's secretary, Miss Featherstone, with her. I've been down at Riversreade Court most of the day, and there's no doubt about it—the two ladies were carried off from there by three men in a fast car, which was driven towards London. That's a fact!"
 
"God bless my soul!" exclaimed Lord Morradale. "In broad daylight! Twentieth century, too! And is there no clue?"
 
"None so far, my lord. Of course, we've noised the affair as much as possible, and all our people are on the look out. But it's a difficult case," continued Matherfield. "The probability is that the ladies have been rushed to some house in London and that they're there in captivity. Of course, one theory is that the kidnappers took Madame Listorelle for her sister. They meant to get Lady Riversreade and hold her to ransom."
 
Lord Morradale pursed his lips. Then he rubbed his chin. Then he shook his head. Finally he gave Hetherwick a shrewd glance, eyeing him from head to foot.
 
"Um!" he said. "Ah! This gentleman? Not one of your people, I think, Matherfield?"
 
"No, my lord. This gentleman is Mr. Hetherwick, of the Middle Temple, who is interested very deeply in certain matters connected with the affair. Mr. Hetherwick has been down to Riversreade with me, and your lordship can speak freely before him."
 
Lord Morradale gave Hetherwick a friendly, knowing nod. Then he glanced at the door, and Matherfield made haste to close it.
 
"T............