The servant said the professor was at home and requested me to follow her. Through open doors I had a glimpse of taste and luxury--softly carpeted rooms, old furniture, good pictures--and then the servant opened a door at the extreme end of the hall and announced me. Astonishment riveted me to the threshold for the moment. Except for a cheap writing-table in the window, a big arm-chair by the fireplace, and two or three common chairs against the wall, this room was empty. There was no carpet on the floor, not a picture on the whitewashed walls. The window had a blind, but no curtains; there were no books, and the appointments of the writing-table were of the simplest kind possible. "Ah, I have been expecting you," said Quarles, crossing from the window to welcome me. A skull-cap covered his silver locks, but he wore no glasses, and to-day there were few signs of age or deterioration of physical or mental force about him. His shuffling gait when he had met me in Blenheim Square that morning had evidently been assumed, and probably he had worn glasses to conceal some of the expression of his face. "You had been expecting me?" I said. "Two days ago I gave the servant instructions to bring you in whenever you came. Zena, my dear, this is Detective Wigan--my granddaughter who often assists me in my work." I bowed to the girl who had risen from the chair at the writing-table, and for a moment forgot the professor--and, indeed, everything else in the world. Since no woman had ever yet succeeded in touching any sympathetic chord in me, it may be assumed that she was remarkable. In that bare room she looked altogether out of place, and yet her presence transformed it into a desirable spot. "You are full of surprises, professor," I said, with a keen desire to make myself agreeable. "I enter your house and have a glimpse of luxury through open doors, yet I find you in--in an empty room; you tell me I am expected, when until a few hours ago I had not determined to call upon you; and now you further mystify me by saying this lady is your helper." "Philosophy is mysterious," he answered, "and I am interested in all the ramifications of my profession. To understand one science perfectly means having a considerable knowledge of all other sciences." "My grandfather exaggerates my usefulness," said the girl. "I do not," he returned. "Your questions have constantly shown me the right road to travel, and to have the right road pointed out is half the battle. Sit down, Mr. Wigan--in the arm-chair--no, I prefer sitting here myself. Zena and I were talking of Blenheim Square when you came in. A coincidence? Perhaps, but it may be something more. In these days we are loath to admit there are things we do not understand. This case puzzles you?" The detective in me was coming slowly uppermost again, and I remembered the line I had decided to take with this curious old gentleman.