DAISY was a little mouse-colored mule.
Nimble-footed as a mountain-goat in the hills she shuffled along under her swaying pack in Singletree Johnson's mule-train, switching her shaven tail in a meditative manner, watching the trail with alert eyes.
No narrow pass fooled Daisy. There was either room for both her and her pack or she stopped until Singletree fixed things to her liking. Once loaded in the morning she was good for all day. As a pack-mule her manners were perfect. But there was another side to Daisy and there -- on hinges Singletree's yarn.
Singletree and his pack-train were known in every border hamlet. His well-fed mules and well-kept equipment drew many envious looks from more careless packers and still more attention from those who live by their wits on both sides of the international boundary line. But Singletree's reputation gave these latter gentry pause. Stealing mules from Singletree was not listed as one of the less hazardous occupations. It was downright dangerous.
But those who peopled Pilares were used to danger and discounted it -- if the odds were right.
On the night of which I speak, Singletree trotted into camp near Pilares, his train, like Mary's little lamb, trailing in behind him. He peeled the packs from his mules, stacked and covered them and set about making ready for the night. The mules, following the old bell mare, Susie, wandered free to graze with the exception of Singletree's saddle mule Jasper. Being a favored mount, Jasper waited near at hand for a nosebag full of grain.
Soon darkness came and the glowing embers of Singletree's fire was the only sign of where the veteran packer was spending the night.
Chico Montes coveted those mules. He knew a ready market where questions were not asked. For "wet" mules or cattle (or Singletree for that matter) presented no great obstacles to Chico. So his plans were made. He would wait with patience until just before the false dawn when men sleep most soundly. Then with stealth and skill he would remove the mules, cross the boundary and leave Singletree to bemoan his loss. He rode by the packer's camp just at dusk, viewed the outfit he already considered his own and was well pleased with the transaction. Singletree appeared in his scheme only as an obstacle to be removed in case he objected.
Chico thought well of himself.

The moon slipped down over the rim of the mountains and even the whistling nightbirds were still when Chico, staking his own horse in a brushy arroyo below the line, started for the packer's camp.
The mules were strung out in irregular line, some grazing quietly, some lying down when Chico walked noiselessly toward them. Susie the old gray bell mare merely lifted her head as Chico approached and with careful hands loosened the bell from her neck. Bell in hand he led the mare away, halting every few steps to permit it to tinkle a note or two as it would on the neck of the grazing mare. The mules, trained to follow Susie, drifted toward the sound. Chico smiled as he saw his plan working smoothly. Then he reached Daisy.
Daisy had been up-wind from the intruder. Even her delicately attuned nose had not detected the presence of the alien visitor until he was almost beside her, guiding old Susie toward the near-by border. A shifting breeze brought Daisy to her feet with a snort, her long ears erect and every muscle quivering. For Daisy did not like Mexicans.
Before Singletree had bought her Daisy had been the property of a Mexican packer and her memory of those days brought both fear and anger. She still bore scars of her earlier master and a mule does not easily forget. The wind told Daisy of trouble and her eyes soon proved her nose correct.
Back by his smoldering campfire Singletree leaped from his blankets as the first wild scream rent the night. Chico had no warning. Daisy had scented him, seen him and charged. With flashing teeth and striking forefeet she had landed on the rustler, knocking him to the ground before he really knew what had hit him. He attempted to run but once more the mouse-colored catamount grabbed him, shaking him with a fury that caused him to drop both the bell and his half-drawn pistol. Chico howled as he tried to break away from the teeth that were clamped on his shoulder. It was like trying to escape from a vise.
Singletree, cursing as he ran across the rocky ground on bootless feet, dashed into the uproar and grabbed Daisy's prey, beating back the angered mule with sharp slaps across the face. Reluctantly Daisy let go and Chico, whimpering in pain, nursed a broken shoulder.
Late the same afternoon Singletree, mounted on Jasper, trotted into Valentine, his sleek and nimble-footed train shuffling along behind him. No one in the ambling line of long-eared burden-bearers appeared more meek and lowly than Daisy.
Lashed atop the pack on one of the larger mules rode a much subdued Chico Montes.
"There's a maverick you can have but his horns are knocked down some. Don't bounce him around too much as you unload him."
"Where did you collect him and what's the charge?" asked the deputy as he surveyed the battered Chico.
"Well," drawled Singletree, "I got him early this morning on the other side of the pass. I guess the only charge against him, aside from intent to steal, would be that he's just plain dumb about mules. Just 'cause she was little and easy-goin' he drifted in and tried to play with Daisy. She did the arrestin' you might say. All I did was the aidin' and abettin'."