When they went to their room—­a room in which there was no bed and they had to roll down their blankets on the floor—­Dan opened the window and commenced to whistle one of his own wild tunes.  It seemed to Calder that there was a break in that music here and there, and a few notes grouped together like a call.  In a moment a shadowy figure leaped through the window, and Black Bart landed on the floor with soft padding feet.

Recovering from his start Calder cursed softly.

“What’s the main idea?” he asked.

Dan made a signal for a lower tone.

“There ain’t no idea,” he answered, “but these Daniels people—­do you know anything about them?”

“No.  Why?”

“They interest me, that’s all.”

“Anything wrong?”

“I guess not.”

“Why did you whistle for this infernal wolf?  It makes me nervous to have him around.  Get out, Bart.”

The wolf turned a languid eye upon the marshal.

“Let him be,” said Dan.  “I don’t feel no ways nacheral without havin’ Bart around.”

The marshal made no farther objections, and having rolled himself in his blankets was almost immediately asleep and breathing heavily.  The moment Dan heard his companion draw breath with a telltale regularity, he sat up again in his blankets.  Bart was instantly at his side.  He patted the shaggy head lightly, and pointed towards the door.

“Guard!” he whispered.

Then he lay down and was immediately asleep.  Bart crouched at his feet with his head pointed directly at the door.

In other rooms there was the sound of the Daniels family going to bed—­noises distinctly heard throughout the flimsy frame of the house.  After that a deep silence fell which lasted many hours, but in that darkest moment which just precedes the dawn, a light creaking came up the hall.  It was very faint and it occurred only at long intervals, but at the first sound Black Bart raised his head from his paws and stared at the door with those glowing eyes which see in the dark.

Now another sound came, still soft, regular.  There was a movement of the door.  In the pitch dark a man could never have noticed it, but it was plainly visible to the wolf.  Still more visible, when the door finally stood wide, was the form of the man who stood in the opening.  In one hand he carried a lantern thoroughly hooded, but not so well wrapped that it kept back a single ray which flashed on a revolver.  The intruder made a step forward, a step as light as the fall of feathers, but it was not half so stealthy as the movement of Black Bart as he slunk towards the door.  He had been warned to watch that door, but it did not need a warning to tell him that a danger was approaching the sleeping master.  In the crouched form of the man, in the cautious step, he recognized the unmistakable stalking of one who hunts.  Another soft step the man made forward.