Lady MacGregor had sat up in order to hear the news, and was delighted with Nevill's plan, especially the part which concerned Stephen, and his proposed adventure on the Charles Quex. Even to hear about it, made her feel young again, she said. Nothing ever happened to her or to Nevill when they were alone, and they ought to be thankful to Stephen for stirring them up. Not one of the three had more than two hours' sleep that night, but according to her nephew, Lady MacGregor looked sweet sixteen when she appeared at an unusually early hour next morning. "No breakfast in bed for me to-day, or for days to come," said she. "I'll have my hands full every instant getting through what I've got to do, I can tell you. Hamish and Angus are worried about my health, but I say to them they needn't grudge me a new interest in life. It's very good for me."

"Why, what have you got to do?" ventured Nevill, who was ready to go with Stephen and buy a berth on board the Charles Quex the moment the office opened.

Lady MacGregor looked at him mysteriously. "Being men, I suppose neither of you would guess," she replied. "But you shall both know after Stephen's adventure is over. I hope you'll like the idea. But if you don't I'm sorry to say it won't make any difference."

The so-called "adventure" had less of excitement in it than had been in the planning. It was faithfully carried out according to Nevill's first suggestion, with a few added details, but Stephen felt incredibly foolish, rather like a Guy Fawkes mummer, or a masked and bedizened guest arriving by mistake the night after the ball. So far as he could see, no one was watching. All his trouble seemed to be for nothing, and he felt that he had made a fool of himself, even when it was over, and he had changed into civilized clothing, in a room in the old town, taken by Adolphe Roslin, the detective. It was arranged for Stephen to wait there, until Roslin could give him news of Si MaÏeddine's movements, lest the Arab should be subtle enough to suspect a trick, after all.

Toward evening the news came. MaÏeddine had taken a ticket for Biskra, and a sleeping berth in the train which would leave at nine o'clock. Nevertheless, Roslin had a man watching Monsieur de Mora's house, in case the buying of the ticket were a "bluff," or Si MaÏeddine should change his plans at the last minute.

Nevill had come in, all excitement, having bought cheap "antique" jewellery in a shop downstairs, by way of an excuse to enter the house. He was with Stephen when Roslin arrived, and they consulted together as to what should be done next.

"Roslin must buy me a ticket for Biskra, of course," said Stephen. "I'll hang about the station in an overcoat with my collar turned up and a cap over my eyes. If MaÏeddine gets into the train I'll get in too, at a respectful distance of course, and keep an eye open to see what he does at each stop."

"There's a change of trains, to-morrow morning," remarked Nevill. "There'll be your difficulty, because after you're out of one train you have to wait for the other. Easy to hide in Algiers station, and make a dash for the end of the train when you're sure of your man. But in a little open, road-side halting-place, in broad daylight, you'll have to be sharp if you don't want him to spot you. Naturally he'll keep his eyes as wide open, all along the line, as you will, even though he does think you're on the way to Marseilles."

"If you're working up to a burnous and painted legs for me again, my dear chap, it's no good," Stephen returned with the calmness of desperation. "I've done with that sort of nonsense; but I won't trust myself out of the train till I see the Arab's back. Then I'll make a bolt for it and dodge him, till the new train's run along the platform and he's safely in it."

"Monsieur has confidence in himself as a detective," smiled Roslin.

Knight could have given a sarcastic answer, since the young man from Marseilles had not made much progress with the seemingly simple case put into his hands a month ago. But both he and Nevill had come to think that the case was not simple, and they were lenient with Roslin. "I hope I'm not conceited," Stephen defended himself, "but I do feel that I can at least keep my end up against this nigger, anyhow till the game's played out so far that he can't stop it."

"And till I'm in it with you," Nevill finished. "By the way, that reminds me. Some one else intends to play the game with us, whether we like or not."

"Who?" asked Stephen, surprised and half defiant.

"My aunt. That's the mystery she was hinting at. You know how unnaturally quiet she was while we arranged that you should look after MaÏeddine, on your own, till the dinner-party was over, anyhow, and I could get off, on a wire from you—wherever you might be?"

"Yes. She seemed interested."

"And busy. Her 'great work' was getting herself ready to follow you with me, in the car."

"Magnificent!" said Stephen. "And like her. Hurrah for Lady MacGregor!"

"I'm glad you take it that way. I wasn't sure you would, which might have made things awkward for me; because when my aunt wants to do a thing, you know by this time as well as I do, it's as good as done."

"But it's splendid—if she can stand the racket. Of course her idea is, that if we find Miss Ray she oughtn't to come back alone with us, perhaps a long way, from some outlandish hole."

"You've got it. That's her argument. Or rather, her mandate. And I believe she's quite able to stand the racket. Her state of mind is such, that if she looked sixteen in the morning, this afternoon she's gone back to fifteen."

"Wonderful old lady! But she's so fragile—and has nervous headaches——"

"She won't have any in my motor car."

"But Hamish and Angus. Can she get on without them?"

"She intends to have them follow her by train, with luggage. She says she has a 'feeling in her bones' that they'll come in handy, either for cooking or fighting. And by Jove, she may be right. She often is. If you go to Biskra and wire when you get there, I'll start at once—we'll start, I mean. And if MaÏeddine goes on anywhere else, and you follow to keep him in sight, I'll probably catch you up with the car, because the railway line ends at Biskra, you know; and beyond, there are only horses or camels."

"Can motors go farther?"

"They can to Touggourt—with 'deeficulty,' as the noble twins would say."

"MaÏeddine may take a car."

"Not likely. Though there's just a chance he might get some European friend with a motor to give him a lift. In that case, you'd be rather stuck."

"Motor cars leave tracks," said Stephen.

"Especially in the desert, where they are quite conspicuous," Nevill agreed. "My aunt will be enchanted with your opinion of her and her plan—but not surprised. She thinks you've twice my sense and knowledge of the world."

Nevill usually enjoyed his own dinner-parties, for he was a born host, and knew that guests were happy in his house. That night, however, was an exception. He was absent-minded, and pulled his moustache, and saw beautiful things in the air over people's heads, so often that not only Lady MacGregor but Angus and Hamish glared at him threateningly. He then did his best to atone; nevertheless, for once he was delighted when every one had gone. At last he was able to read for the second time a letter from Roslin, sent in while dinner was in progress. There had been only time for a glance at it, by begging his friends' indulgence for an instant, while he bolted the news that Stephen had followed MaÏeddine to Biskra. Now, Nevill and Lady MacGregor both hugely enjoyed the details given by Roslin from the report of an employÉ; how cleverly Monsieur had kept out of sight, though the Arab had walked up and down the platform, with two friends, looking about keenly. How, when MaÏeddine was safely housed in his compartment, his companions looking up to his window for a last word, Monsieur Knight had whisked himself into a second-class compartment at the other end of the train.

Next day, about four o'clock, a telegram was brought to Djenan el Djouad. It came from Biskra, and said: "Arrived here. Not spotted. He went house of French commandant with no attempt at concealment. Am waiting. Will wire again soon as have news. Perhaps better not start till you hear."

An hour and a half later a second blue envelope was put into Nevill's hand.

"He and an officer leave for Touggourt in private carriage three horses relays ordered. Have interviewed livery stable. They start at five will travel all night. I follow."

"Probably some officer was going on military business, and MaÏeddine's asked for a lift," Nevill said to Lady MacGregor. "Well, it's too late for us to get away now; but we'll be off as early as you like to-morrow morning."

"If I weren't going, would you start to-day?" his aunt inquired.

"Yes, I suppose so. But——"

"Then please give orders for the car. I'm ready to leave at five minutes' notice, and I can go on as long as you can. I'm looking forward to the trip."

"But I've often offered to take you to Biskra."

"That's different. Now I've got an incentive."