Together they scoured the whole building; no trace of the man could be found. None of the garrison had left his post; every man declared solemnly that no one had entered from outside, nor gone out from within. "If I didn't know you, old man," said Royce, "I should say you had a fit of the jumps. You think it was Goruba?" "It looked very much like that big fellow who collared me. But how could he have got in or out?" "It's decidedly rummy. You remember Goruba came on me suddenly, and John hadn't seen him. Strange that you should have had almost the same experience!" "What did he come for, if it was Goruba? To spy out the position?" "Not easy in the dark. I confess it beats me. How did the fellow get in? It was hardly dark outside, and our men must have seen him, one would think. Yet I believe them." "We had better search for a secret passage to-morrow, though I can't think we should have missed it if there is one. One thing is certain--Goruba has some interest in this fort which we don't know. That explains the persistence of the Tubus." "I wonder! Well, we can't do anything to-night. I only hope it hasn't made our men jumpy. It's an uncanny thing to find an enemy in your midst unawares." CHAPTER XVII A NIGHT ADVENTURE "I am a silly ass," said Challis, as the two returned to the bastion. "Why, what's the matter?" asked Royce, smiling at his companion's disgusted tone. "Why did I shout? If I had held my tongue, we might have kept this matter from the men. As it is, they are sure to have an attack of nerves." "Oh, well! don't worry about it. We can't always do absolutely the best thing. It's a mystery how the fellow got in, and what he was up to. We must watch him if he tries it again." As Challis feared, the men were restless. Nobody had much sleep that night, and the Englishmen were unfeignedly glad when day dawned. The day passed wearisomely. The enemy were seen moving about among the trees, but there was no attack. "You see that spur of forest yonder?" said Royce in the afternoon, pointing to a clump on the north-east side of the fort. "It's only about two hundred yards away, and would be a capital vantage point for an attack. Yet it's the only bit of woodland which the enemy don't appear to occupy. I wonder why?" "Perhaps they think it's a little too near us," suggested Challis. "It's within practically point-blank range of our rifles." "But there are so many of them that they could afford to try a rush from that point. It's very strange. Barring an occasional sniping shot towards evening, nothing has happened from that quarter, and the sniper has never done any damage." "The Tubus' main camp is only a little to the north of it. They may not think it worth while to occupy the second and smaller clump.... Tom, I've been thinking." "The same old problem?"