The Courts of the Morning by John Buchan

Janet's pistol-shot, and the answering shots from the sentries, awakened the camp effectually, but in the thick night, with a volleying wind, it was hard to locate the trouble. Grayne, who was in command, naturally assumed that the danger lay in the neighbourhood of the Gobernador's hut, but Castor was discovered sleeping the heavy sleep of one dosed with aspirin, and Barbara, who slept next door, had heard nothing. The big arc lamps showed everything normal, and, since the light had been promptly switched off in Janet's hut by the raiders, it was presently decided that it had been a false alarm. The arrival of Geordie Hamilton and his garrison from the head of the ravine complicated matters, and it was the better part of an hour before peace was restored. No one doubted that the whole thing had been a blunder of a nervous sentry who had taken a whimsy of the wind for a shot. Barbara went back to bed.

She woke about dawn with an uneasy feeling. Why had Janet not been awakened by the noise -- Janet, the lightest sleeper of them all? It was a mild blue morning after the rain, so she slipped on a dressing-gown and ran across to Janet's hut. To her surprise the door stood open, unlatched. The bed had been slept in, but the occupant had clearly got up and dressed. There was a faint smell which puzzled her, till she realised that it was powder; a shot had been fired in the place during the night. Then she noticed that the floor around the doorway was muddied, and that some of the furniture looked as if it had been violently pushed aside. Lastly, on one of the rafters she observed a jagged splinter which could only have been done by a bullet.