Well, it was not to be expected that these two, so busy with their own affairs, were likely to notice much that was passing around them, as the forenoon sped rapidly away, and Natalie had to think of getting home again.  But the little German maid servant was not so engrossed.  She was letting her clear, observant blue eyes stray from the pretty young ladies riding in the Row to the people walking under the trees, and from them again to the banks of the Serpentine, where the dogs were barking at the ducks.  In doing so she happened to look a little bit behind her; then suddenly she started, and said to herself, ‘Herr Je!’ But the little maid had her wits about her.  She pretended to have seen nothing.  Gradually, however, she lessened the distance between herself and her young mistress; then, when she was quite up to her, and walking abreast with her, she said, in a low, quick voice.

“Fraulein!  Fraulein!”

“What is it, Anneli?”

George Brand was listening too.  He wondered that the girl seemed so excited, and yet spoke low, and kept her eyes fixed on the ground.

“Ah, do not look round, Fraulein!” said she, in the same hurried way.  “Do not look round!  But it is the lady who gave you the locket.  She is walking by the lake.  She is watching you.”

Natalie did not look round.  She turned to her companion, and said, without any agitation whatever,

“Do you remember, dearest?  I showed you the locket, and told you about my mysterious visitor.  Now Anneli says she is walking by the side of the lake.  I may go and speak to her, may I not?  Because it was so wicked of Calabressa to say some one had stolen the locket, and wished to restore it after many years.  I never had any such locket.”

She was talking quite carelessly; it was Brand himself who was most perturbed.  He knew well who that stranger must be, if Anneli’s sharp eyes had not deceived her.

“No, Natalie,” he said, quickly, “you must not go and speak to her; and do not look round, either.  Perhaps she does not wish to be seen:  perhaps she would go away.  Leave it to me, my darling; I will find out all about her for you.”

“But it is very strange,” said the girl.  “I shall begin to be afraid of this emissary of Santa Claus if she continues to be so mysterious; and I do not like mystery:  I think, dearest, I must go and speak to her.  She can not mean me any harm.  She has brought me flowers again and again on my birthday, if it is the same.  She gave me the little locket I showed you.  Why may not I stop and speak to her?”

“Not now, my darling,” he said, putting his hand on her arm.  “Let me find out about her first.”

“And how are you going to do that?  In a few minutes, perhaps, she goes away; and when will you see her again?  It is many months since Anneli saw her last; and Anneli sees everything and everybody.”

“We will cross the bridge,” said he, in a low voice, for he knew not how near the stranger might be, “and walk on to Park Lane.  Anneli must tell us how far she follows.  If she turns aside anywhere I will bid you good-bye and see where she goes.  Do you understand, Natalie?”