A Little Wizard by Stanley J. Weyman

The two had advanced without thought to the foot of the tree which Frank had indicated, and in doing so had quitted the shelter of the rift, from which an open space a dozen yards in width now separated them. The deep shade of the yew-tree which stretched its arms above them still afforded some protection, the glare of the sun on the moorland intensifying its gloom and blackness. But such protection was partial only; it could not avail against persons approaching the tree closely.

The horror of the two may be imagined, therefore, when they awoke suddenly to this fact, and to the conviction that some one was approaching -- nay, was already near. Before Jack's muttered warning had well been uttered, the sharp crack of a stick, broken under foot, and the tones of voices drawing each moment nearer placed the danger beyond dispute.