Royce and the two negroes marched steadily on, stopping only for brief intervals of rest. The track led northwards towards the River Yo and the Tubus' country beyond. Late in the afternoon they came to a spot where the trail forked. It was clear that part of the enemy's force had continued on the direct northward course, while another part, apparently the smaller, had diverged to the east. It took John only a few seconds to determine which of the two parties included the prisoners. Besides the hoof marks, there were many prints of bare feet on the soil, and among these John detected the impressions made by Challis's boots. These were in the direct track going northwards. The track diverging to the east was made by hoofs only. "Dem go to fort, sah--oh yes!" said John. "Why do you think so?" Royce asked. John grinned. "No savvy what for," he said; "savvy all same." Royce was aware that the fort lay eastward of them, but he had supposed that it was rather to the south than to the north. Like many negroes, John, as was afterwards proved, had almost as keen a sense of locality as a wild animal. "If you are right," said Royce, "some of the men have probably ridden to the fort to waylay us on our return. That big fellow must be one of the Tubus." "Him no Tubu, sah," said John decisively. "Big fella too much ugly." As Royce had never seen a Tubu, this statement conveyed nothing to him. Goruba's countenance was certainly of a Nubian cast. But he felt assured that the man had some position of authority among the raiders, and had either sent or led a party to attempt his capture. He was much troubled in mind at the thought of leaving some of the enemy in his rear. His only chance--a slight one at the best--of helping Challis would be wholly destroyed if the party from the fort came up behind him, and discovered him before he had time to go into hiding. There was no sign of that party having already returned and rejoined the main body. The one hope he had was that the men in ambush at the fort, after waiting there all day, had now given up the idea of waylaying him, and had struck into the northward route at some point far ahead. Less than an hour of daylight remained; it would soon be dark, and the Tubus were not more likely than any other native tribe to continue their journey in darkness. So Royce felt that if he escaped notice until sunset he would be pretty safe until next morning dawned. The sun went down, and the three men halted. "Where are we to camp, John?" asked Royce. The Hausa looked around. There was no shelter anywhere on the ground, but at a little distance from the track a solitary large tree reared itself to a height of some fifty feet. "Dat's him, sah!" cried the man. "Sleep in tree; berry nice."