For some days past Miss Rottermeyer had gone about rather silently and as if lost in thought. As twilight fell, and she passed from room to room, or along the long corridors, she was seen to look cautiously behind her, and into the dark corners, as if she thought some one was coming up silently behind her and might unexpectedly give her dress a pull. Nor would she now go alone into some parts of the house. If she visited the upper floor where the grand guest-chambers were, or had to go down into the large drawing room, where every footstep echoed, she called Tinette to accompany her.

For something very strange and mysterious was going on in Mr. Sesemann's house. Every morning, when the servants went downstairs, they found the front door wide open, although nobody could be seen far or near to account for it. During the first few days that this happened every room and corner was searched in great alarm, to see if anything had been stolen, for the general idea was that a thief had been hiding in the house and had gone off in the night with the stolen goods; but not a thing in the house had been touched, everything was safe in its place. The door was doubly locked at night, and for further security the wooden bar was fastened across it; but it was no good—next morning the door again stood open. At last, after a great deal of persuasion from Miss Rottermeyer, Sebastian and John plucked up courage and agreed to sit up one night to watch and see what would happen. Miss Rottermeyer hunted up several weapons belonging to the master, and gave these and a bottle of brandy to them so that their courage might not faint if it came to a fight.

On the appointed night the two sat down and began at once to take some of the strengthening cordial, which at first made them very talkative and then very sleepy, so that they leant back in their seats and became silent. As midnight struck, Sebastian roused himself and called to his companion, who, however, was not easy to wake, and kept rolling his head first to one side and then the other and continuing to sleep. Sebastian began to listen more attentively, for he was wide awake now. He did not feel inclined to go to sleep again, for the stillness was ghostly to him, and he was afraid now to raise his voice to rouse John, so he shook him gently to make him stir. At last, as one struck, John woke up, and came back to the consciousness of why he was sitting in a chair instead of lying in his bed. He got up with a great show of courage and said, "Come, Sebastian, we must go out in the hall and see what is going on; you need not be afraid, just follow me."

Whereupon he opened the door wide and stepped into the hall. Just as he did so a sudden gust of air blew through the open front door and put out the light which John held in his hand. He started back, almost overturning Sebastian, whom he clutched and pulled back into the room, and then shutting the door quickly he turned the key as far as he could make it go. Then he pulled out his matches and lighted his candle again. Sebastian, in the suddenness of the affair, did not know exactly what had happened, for he had not seen the open front door or felt the breeze behind John's broad figure. But now, as he saw the latter in the light, he gave a cry of alarm, for John was trembling all over and was as white as a ghost. "What's the matter? What did you see outside?" asked Sebastian sympathetically.

"The door partly open," gasped John, "and a white figure standing at the top of the steps—there it stood, and then all in a minute it disappeared."

Sebastian felt his blood run cold. The two sat down close to one another and did not dare move again till the morning broke and the streets began to be alive again. Then they left the room together, shut the front door, and went upstairs to tell Miss Rottermeyer of their experience. They had no sooner given her details of the night's experience than she sat down and wrote to Mr. Sesemann, who had never received such a letter before in his life. She could hardly write, she told him, for her fingers were stiff with fear, and Mr. Sesemann must please arrange to come back at once, for dreadful and unaccountable things were taking place at home. Then she entered into particulars of all that had happened, of how the door was found standing open every morning.

Mr. Sesemann answered that it was quite impossible for him to arrange to leave his business and return home at once.

Miss Rottermeyer, however, was determined not to pass any more days in a state of fear, and she knew the right course to pursue. She had as yet said nothing to the children of the ghostly apparitions, for she knew if she did that the children would not remain alone for a single moment, and that might entail discomfort for herself. But now she walked straight off into the study, and there in a low, mysterious voice told the two children everything that had taken place. Clara immediately screamed out that she could not remain another minute alone, her father must come home.

So Miss Rottermeyer wrote another letter to Mr. Sesemann, stating that these unaccountable things that were going on in the house had so affected his daughter's delicate constitution that the worst consequences might be expected. Epileptic fits and St. Vitus's dance often came on suddenly in cases like this, and Clara was liable to be attacked by either if the cause of the general alarm was not removed.

The letter was successful, and two days later Mr. Sesemann arrived home.

Clara greeted him with a cry of joy, and seeing her so lively and apparently as well as ever, his face cleared, and the frown of anxiety passed gradually away from it as he heard from his daughter's own lips that she had nothing the matter with her, and moreover was so delighted to see him that she was quite glad about the ghost, as it was the cause of bringing him home again.

"And how is the ghost getting on?" he asked, turning to Miss Rottermeyer, with a twinkle of amusement in his eye.

"It is no joke, I assure you," replied that lady. "You will not laugh yourself tomorrow morning, Mr. Sesemann; what is going on in the house points to some terrible thing that has taken place in the past and been concealed."

"Well, I know nothing about that," said the master of the house, "but I must beg you not to bring suspicion on my worthy ancestors. And now will you kindly call Sebastian into the dining-room, as I wish to speak to him alone."

Mr. Sesemann had been quite aware that Sebastian and Miss Rottermeyer were not on the best of terms, and he had his ideas about this scare.

"Come here, lad," he said as Sebastian appeared, "and tell me frankly—have you been playing at ghosts to amuse yourself at Miss Rottermeyer's expense?"

"No, on my honor, sir; pray, do not think it; I am very uncomfortable about the matter myself," answered Sebastian with unmistakable truthfulness.

"Well, if that is so, I will show you and John tomorrow morning how ghosts look in the daylight. You ought to be ashamed of yourself, Sebastian, a great strong lad like you, to run away from a ghost! But now go and take a message to my old friend the doctor: give him my kind regards, and ask if he will come to me tonight at nine o'clock without fail; I have come by express from Paris to consult him. I shall want him to spend the night here, so bad a case is it; so will he arrange accordingly. You understand?"

"Yes, sir," replied Sebastian, "I will see to the matter as you wish."

Punctually at nine o'clock, after the children and Miss Rottermeyer had retired, the doctor arrived. He was a grey-haired man with a fresh face, and two bright, kindly eyes. He looked anxious as he walked in, but, on catching sight of his patient, burst out laughing and clapped him on the shoulder. "Well," he said, "you look pretty bad for a person that I am to sit up with all night."

"Patience, friend," answered Mr. Sesemann, "the one you have to sit up for will look a good deal worse when we have once caught him, for there is a ghost in the house!"

The doctor laughed again.

"That's a nice way of showing sympathy, doctor!" continued Mr. Sesemann. "It's a pity my friend Rottermeyer cannot hear you. She is firmly convinced that some old member of the family is wandering about the house doing penance for some awful crime he committed."

"How did she become acquainted with him?" asked the doctor, still very much amused.

So Mr. Sesemann recounted to him how the front door was nightly opened by somebody, according to the testimony of the combined household. The whole thing was either a joke gotten up by some friend of the servants, just to alarm the household while he was away or else it was a thief, who, by leading everybody at first to think there was a ghost, made it safe for himself when he came later to steal, as no one would venture to run out if they heard him.

The two took up their quarters for the night in the same room in which Sebastian and John had kept watch. The door was shut close to prevent the light being seen in the hall outside, which might frighten away the ghost. The gentlemen sat comfortably back in the arm-chairs and began talking of all sorts of things, now and then pausing to take a good draught of wine, and so twelve o'clock struck before they were aware.

"The ghost has got scent of us and is keeping away tonight," said the doctor.

"Wait a bit, it does not generally appear before one o'clock," answered his friend.

They started talking again. One o'clock struck. There was not a sound about the house, nor in the street outside. Suddenly the doctor lifted his finger.

"Hush! Sesemann, don't you hear something?"

They both listened, and they distinctly heard the bar softly pushed aside and then the key turned in the lock and the door opened. Mr. Sesemann put out his hand for his revolver.

"You are not afraid, are you?" said the doctor as he stood up.

"It is better to take precautions," whispered Mr. Sesemann, and seizing one of the lights in his other hand, he followed the doctor, who, armed in like manner with a light and a revolver, went softly on in front. They stepped into the hall. The moonlight was shining in through the open door and fell on a white figure standing motionless in the doorway.

"Who is there?" thundered the doctor in a voice that echoed through the hall, as the two men advanced with lights and weapons towards the figure.

It turned and gave a low cry. There in her little white nightgown stood Heidi, with bare feet, staring with wild eyes at the lights and the revolvers, and trembling from head to foot like a leaf in the wind. The two men looked at one another in surprise.

"Why, I believe it is Heidi," said the doctor.

"Child, what does this mean?" said Mr. Sesemann. "What did you want? why did you come down here?"

White with terror, and hardly able to make her voice heard, Heidi answered, "I don't know."

But now the doctor stepped forward. "This is a matter for me to see to, Sesemann; go back to your chair. I must take the child upstairs to her bed."

And with that he put down his revolver and gently taking the child by the hand led her upstairs. "Don't be frightened," he said as they went up side by side, "it's nothing to be frightened about; it's all right, only just go quietly."

On reaching Heidi's room the doctor put the candle down on the table, and taking Heidi up in his arms laid her on the bed and carefully covered her over. Then he sat down beside her and waited until she had grown quieter and no longer trembled so violently. He then took her hand and said in a kind, soothing voice, "There, now you feel better, and now tell me where you were wanting to go to?"

"I did not want to go anywhere," said Heidi. "I did not know I went downstairs, but all at once I was there."

"I see, and had you been dreaming, so that you seemed to see and hear something very distinctly?"

THE DOCTOR DISCOVERS HEIDI'S HOME-SICKNESS

"Yes, I dream every night, and always about the same things. I think I am back with grandfather, and I hear the sound in the fir trees outside, and I see the stars shining so brightly, and then I open the door quickly and run out, and it is all so beautiful! But when I wake I am still in Frankfurt." And Heidi struggled as she spoke to keep back the sobs which seemed to choke her.

"And have you no pain anywhere? no pain in your head or back?"

"No, only a feeling as if there were a great stone weighing on me here."

"As if you had eaten something that would not go down."

"No, not like that; something heavy as if I wanted to cry very much."

"I see, and then do you have a good cry?"

"Oh, no, I mustn't; Miss Rottermeyer forbade me to cry."

"So you swallow it all down, I suppose? Are you happy here in Frankfurt?"

"Yes," was the low answer; but it sounded more like "No."

"And where did you live with your grandfather?"

"Up on the mountain."

"That wasn't very amusing; rather dull at times, eh?"

"No, no, it was beautiful, beautiful!" Heidi could go no further; the remembrance of the past, the excitement she had just gone through, the long suppressed weeping, were too much for the child's strength; the tears began to fall fast, and she broke into violent weeping.

The doctor patted her head kindly. "There, there, go on crying, it will do you good, and then go to sleep: it will be all right tomorrow."

Then he left the room and went downstairs to Mr. Sesemann; when he was once more sitting in the arm-chair opposite his friend, "Sesemann," he said, "let me first tell you that your little charge is a sleep-walker; she is the ghost who has nightly opened the front door and put your household into this fever of alarm. Secondly, the child is consumed with home-sickness to such an extent that she is nearly a skeleton already, and soon will be quite one; something must be done at once. There is but one remedy and that is to send her back to her native mountain air. So tomorrow the child must start for home; there you have my prescription."

Mr. Sesemann had risen and now paced up and down the room in the greatest state of concern.

"What!" he exclaimed, "the child a sleep-walker and ill! All this has taken place in my house and no one noticed it! And you mean, doctor, that the child who came here happy and healthy, I am to send back to her grandfather a miserable little skeleton? I can't do it; you cannot dream of my doing such a thing! Take the child in hand, do with her what you will, and make her whole and sound, and then she shall go home; but you must cure her first."

"Sesemann," replied the doctor, "this illness of the child's is not one to be cured with pills and powders. The child has not a strong constitution, but if you send her back at once she may recover in the mountain air, if not—you would rather she went back ill than not at all?"

Mr. Sesemann stood still; the doctor's words were a shock to him.

"If you put it so, doctor, there is assuredly only one way—and that is to send her home at once."