A nightingale sang as he sauntered homeward. Possibly, being a French nightingale, she was trying to tell him that there were three people lying very still in the thicket near her.

But men are stupid and nightingales are too busy to bother about trifles when there is courting to be done and nests to be planned and all the antic.i.p.ated excitement of the coming new moon to preoccupy a love-distracted bird.

On a warm, sunny day early in June, toward three o'clock in the afternoon, a peloton of French cavalry en vidette from Delle stopped a rather rickety touring-car several kilometres west of the Swiss frontier and examined the sheaf of papers offered for their inspection by the young man who drove the car.

A yellow-haired girl seated beside him leaned back in her place indifferently to relax her limbs.

From the time she and the young man had left Glenark in Scotland their progress had been a series of similar interruptions.

Everywhere on every road soldiers, constables, military policemen, and gentlemen in mufti had displayed, with varying degrees of civility, a persistent curiosity to inspect such papers as they carried.

On the Channel transport it was the same; the same from Dieppe to Paris; from Paris to Belfort; and now, here within a pebble's toss of the Swiss frontier, military curiosity concerning their papers apparently remained unquenched.

The sous-officier of dragoon-lancers sat his splendid horse and gravely inspected the papers, one by one. Behind him a handful of troopers lolled in their saddles, their lances advanced, their horses swishing their tails at the murderous, green-eyed bremsers which, like other bloodthirsty Teutonic vermin, had their origin in Germany, and raided both French and Swiss frontiers to the cruel discomfort of horses and cattle.

Meanwhile the blond, perplexed boy who was examining the papers of the two motorists, scratched his curly head and rubbed his deeply sunburned nose with a sunburned fist, a visible prey to indecision.

Finally, at his slight gesture, his troopers trotted out and formed around the touring-car.

The boyish sous-officier looked pleasantly at the occupants of the car: "Have the complaisance to follow me--rather slowly if you please," he said; wheeled his horse, and trotted eastward toward the roofs of a little hamlet visible among the trees of the green and rolling countryside.

The young man threw in his clutch and advanced slowly, the cavalry trotting on either side with lances in stirrup-boots and slanting backward from the arm-loops.

There was a barrier beyond and some Alpine infantry on guard; and to the left, a paved street and houses. Half-way down this silent little street they halted: the sous-officier dismounted and opened the door of the tonneau, politely a.s.sisting the girl to alight. Her companion followed her, and the sous-officier conducted them into a stucco house, the worn limestone step of which gave directly on the gra.s.s-grown sidewalk.

"If your papers are in order, as they appear to be," said the youthful sous-officier, "you are expected in Delle. And if it is you indeed whom we expect, then you will know how to answer properly the questions of a gentleman in the adjoining room who is perhaps expecting you." And the young sous-officier opened a door, bowed them into the room beyond, and closed the door behind them. As they entered this room a civilian of fifty, ruddy, powerfully but trimly built, and wearing his white hair clipped close, rose from a swivel chair behind a desk littered with maps and papers.

"Good-afternoon," he said in English. "Be seated if you please. And if you will kindly let me have your papers--thank you."

When the young man and the girl were seated, their suave and ruddy host dropped back onto his swivel chair. For a long while he sat there absently caressing his trim, white moustache, studying their papers with unhurried and minute thoroughness.

Presently he lifted his cold, greyish eyes but not his head, like a man looking up over eyegla.s.ses:

"You are this Kay McKay described here?" he inquired pleasantly. But in his very clear, very cold greyish eyes there was something suggesting the terrifying fixity of a tiger's.

"I am the person described," said the young man quietly.

"And you," turning only his eyes on the young girl, "are Miss Evelyn Erith?"

"I am."

"These, obviously, are your photographs?"

McKay smiled: "Obviously."

"Certainly. And all these other doc.u.ments appear to be in order"--he laid them carelessly on his desk--"IF," he added, "Delle is your ultimate destination and terminal."

"We go farther," said McKay in a low voice.

"Not unless you have something further to offer me in the way of credentials," said the ruddy, white-haired Mr. Recklow, smiling his terrifying smile.

"I might mention a number," began McKay in a voice still lower, "if you are interested in the science of numbers!"

"Really. And what number do you think might interest me?"

"Seventy-six--for example."

"Oh," said the other; "in that case I shall mention the very interesting number, Seventy. And you, Miss Erith?" turning to the yellow-haired girl. "Have you any number to suggest that might interest me?"

"Seventy-seven," she said composedly. Recklow nodded:

"Do you happen to believe, either of you, that, at birth, the hours of our lives are already irrevocably numbered?"

Miss Erith said: "So teach us to number our days that we may apply our hearts unto wisdom."

Recklow got up, made them a bow, and reseated himself. He touched a handbell; the blond sous-officier entered.

"Everything is in order; take care of the car; carry the luggage to the two rooms above," said Recklow.

To McKay and Miss Erith he added: "My name is John Recklow. If you want to rest before you wash up, your rooms are ready. You'll find me here or in the garden behind the house."

Toward sunset they found Recklow in the little garden, seated alone there on a bench looking up at the eastward mountains with the piercing, detached stare of a bird of prey. When they had seated themselves on the faded-green bench on either side of him he said, still gazing toward the mountains: "It's April up there. Dress warmly."

"Which is Mount Terrible?" inquired Miss Erith.

"Those are the lower ridges. The summit is not visible from where we sit," replied Recklow. And, to McKay: "There's some snow there still, I hear."

McKay's upward-turned face was a grim study. Beyond those limestone shouldering heights his terrible Calvary had begun--a progress that had ended in the wreckage of mind and soul had it not been for Chance and Evelyn Erith. After Mount Terrible, with its grim "Great Secret," had come the horrors of the prison camp at Holzminden and its nameless atrocities, his escape to New York, the Hun cipher orders to "silence him," his miraculous rescue and redemption by the girl at his side--and now their dual mission to probe the mystery of Mount Terrible.

"McKay," said Recklow, "I don't know what the particular mission may be that brings you and Miss Erith to the Franco-Swiss frontier. I have been merely instructed to carry out your orders whenever you are in touch with me. And I am ready to do so."

"How much do you know about us?" asked McKay, turning to him an altered face almost marred by hard features which once had been only careworn and stern.

"I know you escaped from the Holzminden prison-camp in Germany; that you were inhumanly treated there by the Boche; that you entered the United States Intelligence Service; and that, whatever may be your business here, I am to help further it at your request." He looked at the girl: "As concerning Miss Erith, I know only that she is in the same Government service as yourself and that I am to afford her any aid she requests."

McKay said, slowly: "My orders are to trust you implicitly. On one subject only am I to remain silent--I am not to confide to anybody the particular object which brings us here."

Recklow nodded: "I understood as much. Also I have been instructed that the Boches are determined to discover your whereabouts and do you in before your mission is accomplished. You, probably, are aware of that, McKay?"

"Yes, I am."

"By the way--you know a Captain Herts?"

"Not personally."

"You've been in communication with him?"

"Yes, for some time."

"Did you wire him from Paris last Thursday?"