He set off then walking up and down the tent-like room they were in, wiping the great drops of dew from his forehead openly as he passed his two friends; but the moment his back was to them the handkerchief glided to his eyes, where other salt drops kept on gathering, to be swept carefully away each time before he turned. "But who is this chief, Emir, or whatever he is?" said the professor, stopping before the doctor and Frank suddenly. "I've never heard of him before." "I know nothing about him whatever, only what I have told you. He is some friend of the Emir's son, and of course belongs to their party." "I suppose so," said the professor excitedly. "Well, it all seems simple enough now, Robert, my son. You must set Ibrahim to work the first time the Emir comes in, and tell him we have discovered that this other Emir's slave--Tut-tut-tut! reduced to camel driving! Poor old Hal! But better that than having his head cut off, eh? Let's see; what was I saying? I remember: that this other Emir's slave is a very dear old friend of ours, and that he must get him set free--or buy him--or let us buy him to come and help us. Oh dear! oh dear! Only fancy coming out to the Soudan to buy our old school-fellow! Then when we have got him we must make our plans and be off some dark night, and--I say, though," he said piteously, after a pause, "that won't do. Sounds childish, doesn't it?" "It would not do," said Frank firmly. "And it does sound childish, my dear Fred," said the doctor; "don't you think so?" "Of course it does," replied the professor. "It would upset everything; but I'm so completely knocked off my balance that I don't know what to propose. Yes, I do. Look here: I know. The poor fellow has been a prisoner for years, and looks old and thin, Frank says. Then we must send Ibrahim at once to tell him help is at hand, and put him out of his misery. No, no, no; that sounds like putting him out of his misery altogether. What do you think, Frank?" "That we have been _very_ careful so far, and have at last been thoroughly successful." "Yes, yes; of course," cried the professor excitedly. "Now we must be more cautious than ever." "Exactly; we must tell Ibrahim not to do the slightest thing to excite suspicion." "I am not going to trust Ibrahim to communicate with Hal," said Frank decisively. "I must do this myself." "You?" cried the doctor in surprise; and the professor looked at him wonderingly. "Why do you both stare at me like that?" said Frank warmly. "How is Ibrahim to get leave to speak to my brother?" "For the matter of that," cried the professor testily, "how are you to manage?" "I don't know yet, but in a way I have been introduced there, and have stood close to the poor fellow. Why may I not manage to go there again? The Emir's son would take me anywhere I wished." "That is true, Fred," said the doctor quietly. "We cannot set anyone else to do this," cried Frank warmly. "This must be my task."