Wingate, after reading the letter, escorted Sheila on a small shopping expedition in the West End. They were going to lunch afterwards at the restaurant in close proximity to Hyde Park Mansions. The shopping finished, Wingate suddenly recollected he must send a wire to the works at Hendon, and they proceeded to the nearest post-office in Edgware Road. It was now a quarter to one, and they had settled to lunch at one o'clock, so they walked along quickly. When within a few yards of the post-office, Sheila laid her hand upon his arm. "Stop a second!" she said in an excited voice. "You see that woman getting out of a taxi. It is Mrs Saxton. Let her get in before we go on." He obeyed. The elegant, fashionably-attired young woman paid the driver, and disappeared within the door. The pair of amateur detectives followed on her heels. Sheila's quick eyes picked her out at once, although the office was full of people. Mrs Saxton was already in one of the little pens, writing a telegram. Unobserved by the woman so busily engaged, Sheila stepped softly behind her, and waited till she had finished. She had splendid eyesight, and she read the words distinctly. They ran as follows: "Herbert. Poste Restante, Brighton. Exercise discretion. Maude." Then she glided away, and, with Wingate, hid herself behind a group of people. She had only met the woman once, but it was just possible she might remember her if their glances met. Mrs Saxton took the telegram to the counter, and they heard her ask how long it would take to get to Brighton. Then, having received an answer to the query, which they could not catch, she went out. They looked at each other eagerly. They had made a discovery, but what were they to do with it? "Ring up Smeaton at once, and tell him," suggested Sheila. "He will know what to do." After a moment's reflection, Wingate agreed that this was the proper course. While they were discussing the point, the man himself hurried in. His quick eye detected them at once, and he joined them. "I've just missed Mrs Saxton--eh?" he queried. Sheila explained to him how they had arrived there by accident, and had seen her stepping out of the taxi. Smeaton went on to explain. "I looked round this morning to see how my men were getting on, and found a taxi waiting before the door. I had to hide when she came out, but one of my men heard her give the address of this office. I picked up another taxi, and drove as hard as I could. My fellow kept the other well in sight, but just as we were gaining on her, I was blocked, and lost three minutes. She came here, of course, to send a wire. But it is only a little delay. I can get hold of that wire very shortly." "But there is no need," cried Sheila triumphantly. "At any rate, for the present. I looked over her shoulder, and read every word of it. I will tell it you."