He hurried on after the man, who had passed the room in which the stores were kept and was going in the direction of the well-yard. His back was towards Challis—a broad back, belonging to a man of huge stature.
"Great snakes!" Challis inwardly ejaculated.
He quickened his pace. The man heard his steps, and glanced round; then dashed through a ruined doorway leading to the well-yard.
Challis gave a shout and rushed after him. It was now dark inside the building, and he groped about without finding the negro. His shout had brought Royce up at a run.
"What is it?" he cried anxiously.
"A strange nigger—a big fellow—Goruba?" said Challis.
"Surely not!" said Royce, flashing his electric torch. "There's no one here.'"
"He's got away. We must search the place."
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?"