"I am to show the red light standing on this side of the Serpentine at the right-hand corner of the bridge," she said slowly, to be sure that she knew what she had to do. "I understand. What shall I say to the man?" "Nothing. He will simply place a box in your hand and walk away. All you have to do is to bring the box to me, and then you shall know all about the matter which strikes you as being so strange. Don't lose any time, please." Indeed, there was no time to be lost, as it would take Patricia some minutes to get her out-of-door things on. She ran up the stairs, and assumed boots in place of slippers, a heavy cloak as the night was damp, a plain cloth toque, and gloves. She then took her umbrella in one hand, the lantern, unlighted, in the other, and descended to say a few last words to Mrs. Pentreddle; or, rather, to hear them, for the old lady gave her no opportunity of speaking. For such a grim, unemotional woman, Mrs. Pentreddle seemed quite excited, although she tried to keep herself calm. But a vivid spot of red was certainly showing itself on either pale cheek. "Show the red light and wait in silence," she directed; "do nothing more, and say nothing at all. Then when you receive the box come back with it at once to me. You thoroughly understand?" "I thoroughly understand." "I am glad. Finally, let me assure you once more that there is nothing dishonest or even wrong about the errand I am sending you on." There was nothing more to be said, and Patricia departed. When she closed the front door of The Home of Art, and found herself in the street, she became aware that the night was damp and dense with fog. The gas-lights, however, shone blurred and vague through the white mists, so there was no need for her to use the lantern. No one was about, not even a policeman--in the curve of the _cul de sac_ at all events; but when she passed into the straight line of Crook Street, she almost fell into the arms of a constable who was standing under a lamp. Patricia paused to ask a question. "Will the fog get worse, officer?" "I think it will, miss," said the man, touching his helmet and bending to look at her face. "I should advise you not to go far." "I am only going to the Park to see a friend," answered Miss Carrol, heedlessly; and then remembering that it was a complete stranger whom she had to see, and one to whom she was not even to speak, she regretted having been so doubtfully truthful. "What is the time?" she asked, to cover her confusion. "Half-past eight o'clock, miss," said the constable, consulting a fat silver watch. "Best go home again, miss. You might get lost in this fog, and in the Park there are some rough characters about."