He looked at her with a smile.  “It contains my treasures—­my black arts,” he said, “and my future.”  He pushed it back again and turned.  “Come! we will find the naughty Cinders.”

Chris was on the point of asking eager questions regarding this new mystery, but before she could begin to utter them a long and piteous howl—­the howl of a lost dog—­sent them helter-skelter from her mind.

“Oh, listen!” she cried.  “That’s Cinders!”

She sprang forward while the miserable sound was still echoing all about them.  “Oh, isn’t it dreadful?” she gasped.  “Do you think he is hurt?”

“No, no!” Bertrand hastened to reassure her.  “He is only afraid.  We will go to him.”

He stretched out a hand to her, and she put hers into it as naturally as a child.  Her chin was quivering, and her voice, when she tried to call to the dog, broke down upon a sob.

“He will never know where we are because of the echoes,” she said.

“He is not far,” declared the Frenchman consolingly.  “See, here is the passage.  They say that it was made by the contrabandists, but it leads to nowhere; it has been blocked since many years.  Do not fall on the stones; they are very slippery.”

A passage, even narrower than the first, led from the cave in which they had been standing.  Bertrand went first, his hand stretched out behind him, still holding hers.

They had scrambled in this order about a dozen yards when again they heard Cinders’ cry for help—­a pathetic yelping considerably farther away than it had been before.  The unlucky wanderer seemed to have lost his head in the darkness and to be running hither and thither in wild dismay.

“What shall we do?” said Chris in tears.  “I’ve never heard him cry like that before.”

Bertrand paused to listen.  “The passage divides near here,” he said.  “Courage, little one!  We may find him at any moment.  Will you then wait while I search a little farther?  I will leave you the lantern.  I have some matches.”

“Oh, please don’t leave me!” entreated Chris.  “Why can’t I come too?”

“It is too rough for you,” he said.  “And there are two passages.  If I do not find him in the one, without doubt he will return by the other to you.”

“You—­you’d better take the lantern then,” said Chris, with a gulp.  “If I am only going to stand still, I—­I shan’t want it.”

“No, no—­” he began.

But she insisted.  “Yes, really.  You will want it.  I will wait for you here, if you think it best.  Only you will promise not to be long?”

“I promise,” he said.

“Then be quick and go,” she urged, drawing her hand from his.  “We must find him—­we must.”

But when his back was turned, and she saw him receding from her with the light, she covered her face and trembled.  It was the most horrible adventure she had ever experienced.

For a long time she heard his footsteps echoing weirdly, but when they died away at last and she stood alone in the utter, vault-like darkness, her heart failed her.  What if he also lost his way?