Indeed the fact that nothing did occur was in itself suspicious. For there was hardly a sign of life about the house. No man left it in the morning bound for business. No woman emerged from its door to go shopping of an afternoon. For days at a time nobody entered or left the place, excepting the grocer's boy who came with food.
Then one day a motor-car, with its top raised, chugged up the highway and climbed the steep driveway to the house on the cliff. Henry was in the attic gable on watch and he promptly notified his comrades. There was a rush for the third story, and four heads crowded close together as four pairs of eyes sought to identify the make and number of the car. But the name-plate was missing, and the license tag was so dusty that the number could not be read.
"Run down to the pines with this, quick," said Captain Hardy, thrusting his field-glasses into Willie's hand, "and get the number of that car. See if you can tell what make it is and look for distinguishing marks."
Willie scrambled down the slope through the concealing shrubbery and approached the house as near as he dared. But he had hardly reached his station when the driver ran down the steps of the house, sprang to the wheel, and was off at a fast pace. Willie climbed cautiously back to headquarters.
"Did you get its number?" asked his chief.
"No," replied Willie. "It was covered with dust. And I couldn't tell what make of car it was. But I saw the driver and I am sure I have seen him before and the car, too."
"That's not unlikely," said Captain Hardy, "if he lives anywhere near here. We've been here several days now."
"I'm sure I've seen that man somewhere," said Willie. "I wish I could remember where it was."
Another day passed and another, and still the little house on the cliff showed no signs of life. But one afternoon the monotonous watch came to a sudden end. Lew, in the attic gable, espied a fleet of transports coming down the bay. Instantly he spread the alarm.
"You boys slip down to the pines," said Captain Hardy to Willie and Roy. "If any one comes out of the house trail him. Now we'll find out whether this spy--if he be a spy--telephones his news or sends it out by messenger. The Chief has had the telephone wires tapped and is receiving a record of all conversations."