Poor souls, he thought, nothing was likely to come out of their zeal.

But it would please them to think they were at least doing something towards the unravelling of the mystery.

In this supposition he was destined to be agreeably disappointed in the next few hours.

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.

Un.o.bserved 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."

She repeated the words. He had showed obvious signs of vexation at having just missed the woman he was hunting, and now his brow cleared.

"Very clever of you. Miss Monkton--very clever," he said in appreciative tones. "Now, who is Herbert, that's the question?"

"Stent, no doubt," suggested Wingate, with a certain amount of rashness.

The detective regarded him with his kindly but somewhat quizzical smile.

"I very much doubt if it is Stent, Mr Wingate. I sent a man down early this morning to St Albans, where I believe he lives. I should say Herbert is another man altogether." The young people readily accepted the professional's theory. They recognised that they were only amateurs.

There was a long pause. They stood humbly waiting for the great man to speak, this man of lightning intuition and strategic resource.

It seemed an interminable time to the expectant listeners before he again opened his lips. Before he did speak, he pulled out his watch and noted the time.

"This may be important, and we cannot afford to lose a moment," he said at length. "How do you stand, Mr Wingate, as regards time? Can you spare me the whole of the day?"

"The whole of to-day, to-morrow, and the next day, if it will help,"

cried the young man fervently.

"There is a fairly fast train from Victoria in forty minutes from now.

You have plenty of time to catch it. I want you to go to the post-office in Brighton, and get hold of that telegram."

"But it is addressed to the name of Herbert."

"No matter," said Smeaton, a little impatiently. "If the real Herbert has not been before you--and I should guess it is an unexpected message--they will hand it to you; they are too busy to be particular.

If he has already been, trump up a tale that he is a friend of yours, and not being sure that he would be able to call himself, had asked you to look in for it, so as to make sure."

"I see," said Wingate. He felt an increased admiration for the professional detective. He was not quite sure that he would have been ready with this glib explanation.

"I should love to go too," said Sheila, looking wistfully at the ever-resourceful Smeaton, whom she now frankly accepted as the disposer of their destinies.

"Forgive me if I oppose you this once, my dear Miss Monkton," he said in his kindest and most diplomatic manner. "Two are not always company in detective business, unless they've been trained to work together.

Besides, I shall want Mr Wingate to keep in close touch with me on the 'phone, and he will have no time to look after a lady."

Having settled that matter, he turned to Wingate. "First of all, here are a couple of my cards; one to show the post-office if there is anything awkward--this for the chief constable of Brighton if you have need of his a.s.sistance. I will scribble an introduction on it." He suited the action to the word. "Now, the sooner you are off the better.

I will put Miss Monkton into a taxi. You be off, and try to get hold of that wire."

There was no resisting his powerful personality. He controlled the situation like an autocrat.

"Stay, just one thing more. I shall be at Scotland Yard till seven, and at home about eight. Here is my private 'phone number, if unseen developments arise."

He thought of everything, he foresaw the improbable. They were lost in admiration. At the moment of departing, he rather damped their enthusiasm by muttering, almost to himself:

"If I could put my hand on one of my own men, I wouldn't trouble you, but there is no time, and delay is dangerous."

A hasty hand-shake to Sheila, a fond lover's look into her eyes, and Wingate was out of the post-office, and into a taxi, en route for Victoria.

He thought of her all the time he was travelling to Brighton. In these last few days her great sorrow had brought her very near to him. He had read her disappointment when Smeaton had forbidden her to accompany him.

But she would not resent that on him; she knew he was working in her interests, that his one thought was to help in solving the tragic mystery that was clouding her young life.

The train arrived at Brighton punctual to the minute, and mindful of Smeaton's remark that delay was dangerous, he drove straight to the post-office.

He was, in a certain sense, elated with the mission that had been entrusted him, through the mere accident of Smeaton not having had time to put his hand on an experienced man. But he felt some trepidation as he walked through the swing-doors. Surely people who set forth on detective work must have nerves of steel and foreheads of triple bra.s.s.

He bought some stamps first, not because he wanted them, but in order to screw up his courage to sticking-point.

A sharp-featured, not too amiable-looking young woman served him. When he had completed his purchase, he asked in as cordial a voice as he could a.s.sume:

"Are there any letters or telegrams for the name of Herbert?"

The young woman regarded him with a suspicious glance.