Daughters of Destiny by L. Frank Baum

David was in high spirits. True, these absurd Americans had virtually made him a prisoner in their house until his services were required to lead them to the harem of the khan; but he had been clever enough to arrange all his plans beforehand. Now, as he sat in the dim room awaiting the hour of action, he felt he had good reason to congratulate himself. The service of the vizier had been especially remunerative, for in addition to his liberal pay as a spy he had that morning received from Maie a large sum to keep her secret, with a promise of more to follow, and then he had secured an equal sum from Agahr for betraying his daughter's secret. Was that not clever? Allison, also, who now sat opposite him silently smoking and at times stealthily glancing at his watch, had contributed much money for the preservation of a secret that was a secret no longer. There were three good strings to that bow, thought David, chuckling delightedly. And now the old underground passage into the khan's harem, which the Jew had discovered long ago and feared he would never have any use for, had paid him richer returns than all else. Mentally he figured up his various accumulations, both in money and jewels, and decided he was too rich to remain longer in Mekran. He would return very soon to Kelat, where there was more room for enterprise; or perhaps he would go on to Quettah, or even so far as --

"Come! " said the Colonel's voice, its stern tones interrupting David's meditations; "we are ready."