If I am discovered and fail I shall cry out ‘For Helium!’ and that must be your signal to escape as best you may.

She laid her hand upon my arm. "Let me go into the courtyard with you," she begged. "Two swords are better than one."

"No," I said. "Alone I have a better chance of handling the thoats than if their attention is distracted by another."

"Very well," she said, and with that I left her, and re-entering the chamber, went directly to the window. For a moment I reconnoitered the interior of the courtyard and finding conditions unchanged, I slipped stealthily through the window and edged slowly toward the gate. Cautiously I examined the latch and discovering it easy to manipulate, I was soon silently pushing one of the gates back upon its hinges. When it was opened sufficiently wide to permit the passage of a thoat, I turned my attention to the beasts within the enclosure. Practically untamed, these savage creatures are as wild as their uncaptured fellows of the remote sea bottoms, and, being controlled solely by telepathic means, they are amenable only to the suggestion of the more powerful minds of their masters and even so it requires considerable skill to dominate them.

I had learned the method from Tar Tarkas himself and had come to feel considerable proficiency so that I approached this crucial test of my power with the confidence that was absolutely requisite to success.

Placing myself close beside the gate, I concentrated every faculty of my mind to the direction of my will, telepathically, upon the brain of the thoat I had selected for my purpose, the selection being determined solely by the fact that he stood nearest to me. The effect of my effort was immediately apparent. The creature, which had been searching for the occasional tufts of moss that grew between the stone flags of the courtyard, raised his head and looked about him. At once he became restless, but he gave forth no sound since I was willing him to silence. Presently his eyes moved in my direction and halted upon me. Then, slowly, I drew him toward me. It was slow work, for he evidently sensed that I was not his master, but on he came. Once, when he was quite near me, he stopped and snorted angrily. He must have caught my scent then and realized that I was not even of the same race as that to which he was accustomed. Then it was that I exerted to their fullest extent every power of my mind. He stood there shaking his ugly head to and fro, his snarling lips baring his great fangs. Beyond him I could see that the other thoats, had been attracted by his actions. They were looking toward us and moving about restlessly, always drawing closer. Should they discover me and start to squeal, which is the first and always ready sign of their easily aroused anger, I knew that I should have their riders upon me in no time, since because of his nervous and irritable nature the thoat is the watchdog as well as the beast of burden of the green Barsoomians.

For a moment the beast I had selected hesitated before me as though undecided whether to retreat or to charge, but he did neither; instead he came slowly up to me and as I backed through the gate into the vaulted corridor beyond, he followed me. This was better than I had expected for it permitted me to compel him to lie down, so that the girl and I were able to mount with ease.

Before us lay a long vaulted corridor at the far end of which I could discern a moonlit archway, through which we presently passed onto a broad avenue.

To the left lay the bills, and, turning this way, I urged the fleet animal along the ancient deserted thoroughfare between rows of stately ruins toward the west and - what?

Where the avenue turned to wind upward into the hills, I glanced back; nor could I refrain a feeling of exultation as I saw strung out behind us in the moonlight a file of great thoats, which I was confident would well know what to do with their new found liberty.

"Your captors will not pursue us far," I said to the girl, indicating the thoats with a nod of my head.

"Our ancestors are with us tonight," she said. "Let us pray that they may never desert us."

Now, for the first time, I had a fairly good look at my companion, for both Cluros and Thuria were in the heavens and it was quite light. If I revealed my surprise it is not to be wondered at for, in the darkness, having only my companion’s voice for a guide, I had been perfectly confident that I had given aid to a female, but now as I looked at that short hair and boyish face I did not know what to think; nor did the harness that my companion wore aid me in justifying my first conclusion, since it was quite evidently the harness of a man.

"I thought you were a girl," I blurted out.

A fine mouth spread into a smile that revealed strong, white teeth. "I am," she said.

"But your hair - your harness - even your figure belies your claim."

She laughed gayly. That, I was to find later, was one of her chiefest charms - that she could laugh so easily, yet never to wound.

"My voice betrayed me," she said. "It is too bad."

"Why is it too bad?" I asked.

"Because you would have felt better with a fighting man as a companion, whereas now you feel that you have only a burden."

"A light one," I replied, recalling how easily I had lifted her to the thoat’s back. "But tell me who you are and why you are masquerading as a boy."

"I am a slave girl," she said; "just a slave girl who has run away from her master. Perhaps that will make a difference," she added a little sadly. "Perhaps you will be sorry that you have defended just a slave girl."

"No," I said, "that makes no difference.