The Summons by A.E.W. Mason

At six o'clock in the evening Colin Rayne, a young civilian in the Sudan Service, heard, as he sat on the balcony of the mess at Senga, the rhythmical thud of camels swinging in to their rest in the freshness of the night air.

"There's our man," he exclaimed, and running downstairs, he reached the door just as Hillyard's twelve camels and his donkeys trooped into the light. Hillyard was riding bareheaded, with his helmet looped to his saddle, a young man, worn thin by sun and exercise, with fair burnt hair, and a brown clean shaven face. Colin Rayne went up to him as he dismounted.