And this she had quite evidently done. The door of the cab opposite him stood open. No doubt she had purposely refrained from closing it, fearing that the click of the lock might attract the driver's attention. The latter with his eyes following Duvall, as the detective entered the store, had remained serenely unconscious of his passenger's movements, her clever escape.
At least three or four minutes had elapsed. Duvall glanced up and down the street, but no sight of the vanished woman greeted his anxious gaze. She had had ample time to reach the next corner, and disappear in the darkness. Thoughts of pursuit entered his mind, but he realized at once the fruitlessness of such an attempt. His captive might have fled east or west, at either of the streets north or south of where he stood. Or she might have entered some restaurant, some motion picture house, or other convenient doorway along the Avenue. She might even have boarded a Sixth Avenue car, or hailed a passing cab. He looked up at the chauffeur, who still sat at his steering wheel, totally unaware of the flight of one of his passengers.
"The woman has gone," Duvall exclaimed, nodding toward the vacant cab.
The man turned in complete surprise. He seemed scarcely able to credit the evidence of his senses.
"I--why sir--she was here just a moment ago, sir," he gasped, gazing into the interior of the cab as though he expected its recent occupant to suddenly materialize in the flesh.
"She got out on the other side, while I was in the store," Duvall remarked, shortly, then taking an electric searchlight from his pocket, made a thorough examination of the interior of the cab. He scarcely expected to find anything, although it flashed through his mind that the woman, in her hurry to escape, might have left her bag, her gloves, or something that might afford him a clue to her identity.
At first he saw nothing. Then, as his eyes became more accustomed to the brilliant glare of the electric torch, he observed a bit of white cardboard lying on the floor. It looked like a visiting card, and he snatched it up, devoutly hoping that it had fallen from the woman's bag during the attempt he had made to rifle it.
Under the light of his pocket lamp he made a quick examination of his find. It proved a lamentable disappointment. It was in fact a visiting card, or to be more correct, the torn half of one, but what was engraved upon it afforded him not the least clue to either the identity or the address of the woman he sought. On the first line were the words, "Miss Mar"--then came the torn edge of the card. On the second line there was but the figure 1, and then the break.