At the head of the first flight of a dingy staircase leading up from an ever-open portal in a street by the Strand stood a door, the dusty ground-glass upper panel of which carried in its centre the single word "Hewitt," while at its right-hand lower corner, in smaller letters, "Clerk's Office" appeared. On a morning when the clerks in the ground-floor offices had barely hung up their hats, a short, well-dressed young man, wearing spectacles, hastening to open the dusty door, ran into the arms of another man who suddenly issued from it. [Illustration: MARTIN HEWITT.] "I beg pardon," the first said. "Is this Hewitt's Detective Agency Office?" "Yes, I believe you will find it so," the other replied. He was a stoutish, clean-shaven man, of middle height, and of a cheerful, round countenance. "You'd better speak to the clerk." In the little outer office the visitor was met by a sharp lad with inky fingers, who presented him with a pen and a printed slip. The printed slip having been filled with the visitor's name and present business, and conveyed through an inner door, the lad reappeared with an invitation to the private office. There, behind a writing-table, sat the stoutish man himself, who had only just advised an appeal to the clerk. "Good morning, Mr. Lloyd--Mr. Vernon Lloyd," he said, affably, looking again at the slip. "You'll excuse my care to start even with my visitors--I must, you know. You come from Sir James Norris, I see." "Yes; I am his secretary. I have only to ask you to go straight to Lenton Croft at once, if you can, on very important business. Sir James would have wired, but had not your precise address. Can you go by the next train? Eleven-thirty is the first available from Paddington." "Quite possibly. Do you know anything of the business?" "It is a case of a robbery in the house, or, rather, I fancy, of several robberies. Jewellery has been stolen from rooms occupied by visitors to the Croft. The first case occurred some months ago--nearly a year ago, in fact. Last night there was another. But I think you had better get the details on the spot; Sir James has told me to telegraph if you are coming, so that he may meet you himself at the station; and I must hurry, as his drive to the station will be rather a long one. Then I take it you will go, Mr. Hewitt? Twyford is the station." "Yes, I shall come, and by the eleven-thirty. Are you going by that train yourself?" "No, I have several things to attend to now I am in town. Good morning; I shall wire at once." Mr. Martin Hewitt locked the drawer of his table and sent his clerk for a cab.