On the following morning, just before lunch, a lady, accompanied by a maid and a considerable quantity of luggage, came to the Grand Babylon Hotel. She was a plump, little old lady, with white hair and an old-fashioned bonnet, and she had a quaint, simple smile of surprise at everything in general.

Nevertheless, she gave the impression of belonging to some aristocracy, though not the English aristocracy. Her tone to her maid, whom she addressed in broken English — the girl being apparently English — was distinctly insolent, with the calm, unconscious insolence peculiar to a certain type of Continental nobility. The name on the lady's card ran thus: 'Baroness Zerlinski'. She desired rooms on the third floor. It happened that Nella was in the bureau.

'On the third floor, madam?' questioned Nella, in her best clerkly manner.

'I did say on de tird floor,' said the plump little old lady.

'We have accommodation on the second floor.'

'I wish to be high up, out of de dust and in de light,' explained the Baroness.

'We have no suites on the third floor, madam.'

'Never mind, no mattaire! Have you not two rooms that communicate?'

Nella consulted her books, rather awkwardly.

'Numbers 122 and 123 communicate.'

'Or is it 121 and 122? the little old lady remarked quickly, and then bit her lip.

'I beg your pardon. I should have said 121 and 122.'

At the moment Nella regarded the Baroness's correction of her figures as a curious chance, but afterwards, when the Baroness had ascended in the lift, the thing struck her as somewhat strange. Perhaps the Baroness Zerlinski had stayed at the hotel before. For the sake of convenience an index of visitors to the hotel was kept and the index extended back for thirty years. Nella examined it, but it did not contain the name of Zerlinski. Then it was that Nella began to imagine, what had swiftly crossed her mind when first the Baroness presented herself at the bureau, that the features of the Baroness were remotely familiar to her. She thought, not that she had seen the old lady's face before, but that she had seen somewhere, some time, a face of a similar cast. It occurred to Nella to look at the 'Almanach de Gotha' — that record of all the mazes of Continental blue blood; but the 'Almanach de Gotha' made no reference to any barony of Zerlinski. Nella inquired where the Baroness meant to take lunch, and was informed that a table had been reserved for her in the dining-room, and she at once decided to lunch in the dining-room herself. Seated in a corner, half-hidden by a pillar, she could survey all the guests, and watch each group as it entered or left.

Presently the Baroness appeared, dressed in black, with a tiny lace shawl, despite the June warmth; very stately, very quaint, and gently smiling. Nella observed her intently. The lady ate heartily, working without haste and without delay through the elaborate menu of the luncheon. Nella noticed that she had beautiful white teeth. Then a remarkable thing happened. A cream puff was served to the Baroness by way of sweets, and Nella was astonished to see the little lady remove the top, and with a spoon quietly take something from the interior which looked like a piece of folded paper. No one who had not been watching with the eye of a lynx would have noticed anything extraordinary in the action; indeed, the chances were nine hundred and ninety-nine to one that it would pass unheeded. But, unfortunately for the Baroness, it was the thousandth chance that happened. Nella jumped up, and walking over to the Baroness, said to her:

'I'm afraid that the tart is not quite nice, your ladyship.'

'Thanks, it is delightful,' said the Baroness coldly; her smile had vanished. 'Who are you? I thought you were de bureau clerk.'

'My father is the owner of this hoteL I thought there was something in the tart which ought not to have been there.'

Nella looked the Baroness full in the face. The piece of folded paper, to which a little cream had attached itself, lay under the edge of a plate.

'No, thanks.' The Baroness smiled her simple smile.

Nella departed. She had noticed one trifling thing besides the paper — namely, that the Baroness could pronounce the English 'th' sound if she chose.

That afternoon, in her own room, Nella sat meditating at the window for long time, and then she suddenly sprang up, her eyes brightening.

'I know,' she exclaimed, clapping her hands. 'It's Miss Spencer, disguised!

Why didn't I think of that before?' Her thoughts ran instantly to Prince Aribert. 'Perhaps I can help him,' she said to herself, and gave a little sigh. She went down to the office and inquired whether the Baroness had given any instructions about dinner. She felt that some plan must be formulated. She wanted to get hold of Rocco, and put him in the rack. She knew now that Rocco, the unequalled, was also concerned in this mysterious affair.

'The Baroness Zerlinski has left, about a quarter of an hour ago,' said the attendant.

'But she only arrived this morning.'

'The Baroness's maid said that her mistress had received a telegram and must leave at once. The Baroness paid the bill, and went away in a four-wheeler.'

'Where to? 'The trunks were labelled for Ostend.'

Perhaps it was instinct, perhaps it was the mere spirit of adventure; but that evening Nella was to be seen of all men on the steamer for Ostend which leaves Dover at 11 p.m. She told no one of her intentions — not even her father, who was not in the hotel when she left. She had scribbled a brief note to him to expect her back in a day or two, and had posted this at Dover. The steamer was the Marie Henriette, a large and luxurious boat, whose state-rooms on deck vie with the glories of the Cunard and White Star liners. One of these state-rooms, the best, was evidently occupied, for every curtain of its windows was carefully drawn. Nella did not hope that the Baroness was on board; it was quite possible for the Baroness to have caught the eight o'clock steamer, and it was also possible for the Baroness not to have gone to Ostend at all, but to some other place in an entirely different direction. Nevertheless, Nella had a faint hope that the lady who called herself Zerlinski might be in that curtained stateroom, and throughout the smooth moonlit voyage she never once relaxed her observation of its doors and its windows.

The Maria Henriette arrived in Ostend Harbour punctually at 2 a.m. in the morning. There was the usual heterogeneous, gesticulating crowd on the quay.

Nella kept her post near the door of the state-room, and at length she was rewarded by seeing it open. Four middle-aged Englishmen issued from it. From a glimpse of the interior Nella saw that they had spent the voyage in card-playing.

It would not be too much to say that she was distinctly annoyed. She pretended to be annoyed with circumstances, but really she was annoyed with Nella Racksole. At two in the morning, without luggage, without any companionship, and without a plan of campaign, she found herself in a strange foreign port — a port of evil repute, possessing some of the worst-managed hotels in Europe. She strolled on the quay for a few minutes, and then she saw the smoke of another steamer in the offing. She inquired from an official what that steamer might be, and was told that it was the eight o'clock from Dover, which had broken down, put into Calais for some slight necessary repairs, and was arriving at its destination nearly four hours late. Her mercurial spirits rose again. A minute ago she was regarding herself as no better than a ninny engaged in a wild-goose chase. Now she felt that after all she had been very sagacious and cunning. She was morally sure that she would find the Zerlinski woman on this second steamer, and she took all the credit to herself in advance. Such is human nature.

The steamer seemed interminably slow in coming into harbour. Nella walked on the Digue for a few minutes to watch it the better. The town was silent and almost deserted. It had a false and sinister aspect. She remembered tales which she had heard of this glittering resort, which in the season holds more scoundrels than any place in Europe, save only Monte Carlo. She remembered that the gilded adventures of every nation under the sun forgathered there either for business or pleasure, and that some of the most wonderful crimes of the latter half of the century had been schemed and matured in that haunt of cosmopolitan iniquity.

When the second steamer arrived Nella stood at the end of the gangway, close to the ticket-collector. The first person to step on shore was - not the Baroness Zerlinski, but Miss Spencer herself! Nella turned aside instantly, hiding her face, and Miss Spencer, carrying a small bag, hurried with assured footsteps to the Custom House. It seemed as if she knew the port of Ostend fairly well. The moon shone like day, and Nella had full opportunity to observe her quarry. She could see now quite plainly that the Baroness Zerlinski had been only Miss Spencer in disguise. There was the same gait, the same movement of the head and of the hips; the white hair was easily to be accounted for by a wig, and the wrinkles by a paint brush and some grease paints. Miss Spencer, whose hair was now its old accustomed yellow, got through the Custom House without difficulty, and Nella saw her call a closed carriage and say something to the driver. The vehicle drove off. Nella jumped into the next carriage — an open one — that came up.

'Follow that carriage,' she said succinctly to the driver in French.

'Bien, madame!' The driver whipped up his horse, and the animal shot forward with a terrific clatter over the cobbles. It appeared that this driver was quite accustomed to following other carriages.

'Now I am fairly in for it!' said Nella to herself. She laughed unsteadily, but her heart was beating with an extraordinary thump.

For some time the pursued vehicle kept well in front. It crossed the town nearly from end to end, and plunged into a maze of small streets far on the south side of the Kursaal. Then gradually Nella's equipage began to overtake it. The first carriage stopped with a jerk before a tall dark house, and Miss Spencer emerged. Nella called to her driver to stop, but he, determined to be in at the death, was engaged in whipping his horse, and he completely ignored her commands. He drew up triumphantly at the tall dark house just at the moment when Miss Spencer disappeared into it. The other carriage drove away. Nella, uncertain what to do, stepped down from her carriage and gave the driver some money. At the same moment a man reopened the door of the house, which had closed on Miss Spencer.

'I want to see Miss Spencer,' said Nella impulsively. She couldn't think of anything else to say.

'Miss Spencer? 'Yes; she's just arrived.'

'It's O.K., I suppose,' said the man.

'I guess so,' said Nella, and she walked past him into the house. She was astonished at her own audacity.

Miss Spencer was just going into a room off the narrow hall. Nella followed her into the apartment, which was shabbily furnished in the Belgian lodging-house style.

'Well, Miss Spencer,' she greeted the former Baroness Zerlinski, 'I guess you didn't expect to see me. You left our hotel very suddenly this afternoon, and you left it very suddenly a few days ago; and so I've just called to make a few inquiries.'

To do the lady justice, Miss Spencer bore the surprising ordeal very well.

She did not flinch; she betrayed no emotion. The sole sign of perturbation was in her hurried breathing.

'You have ceased to be the Baroness Zerlinski,' Nella continued. 'May I sit down?'

'Certainly, sit down,' said Miss Spencer, copying the girl's tone. 'You are a fairly smart young woman, that I will say. What do you want? Weren't my books all straight?'

'Your books were all straight. I haven't come about your books. I have come about the murder of Reginald Dimmock, the disappearance of his corpse, and the disappearance of Prince Eugen of Posen. I thought you might be able to help me in some investigations which I am making.'

Miss Spencer's eyes gleamed, and she stood up and moved swiftly to the mantelpiece.

'You may be a Yankee, but you're a fool,' she said.

She took hold of the bell-rope.

'Don't ring that bell if you value your life,' said Nella.

'If what?' Miss Spencer remarked.

'If you value your life,' said Nella calmly, and with the words she pulled from her pocket a very neat and dainty little revolver.