"I suspect them all right, but how can we prove it?" "I have an idea," Hugh exclaimed suddenly. The two boys were standing on the opposite side of the street from the Wernbergs' house, regarding it curiously. "What is it?" "Can you get your automobile?" "I guess so, if Heinrich hasn't taken the family out." "Let's get it and follow one of those machines. In that way we can see where the people live who are at the Wernbergs'. Maybe we can learn something about them if we know who they are." "A good scheme," exclaimed Bob readily. "We'll have to be awfully careful though; if they ever found out we were following them it might go hard with us." "We'll be careful all right," said Hugh grimly. "Come ahead, we want to be ready to start and they may leave at any time." The two boys walked quickly up the street, taking care to keep on the opposite side from the Wernberg home. When they arrived in front of the Cooks' they darted across the street and hurried along the driveway until they came to the garage. The door was shut and locked. Bob knocked loudly. There was no reply. Bob looked at his watch under the light of a match which Hugh struck. It was twenty minutes of eleven. "That's queer," he muttered. "Heinie is usually in bed long before this." "Maybe he is now, and is asleep," Hugh suggested. Bob glanced up at the second story window. "I don't think so," he said. "The window is closed in the room where he usually sleeps, and I know he is a crank on fresh air." "Throw some gravel at it," said Hugh. "That'll get him up if he's there." This plan was followed, but with no success. "He's out," said Bob finally. "What'll we do?" "Is the car there?" "Yes, but what good will it do us if we can't get in?" "Haven't you got a key to the garage up at the house?" "Father has one, but I don't dare wake him now." Bob glanced at the house and the absence of lights on the first and second floors convinced him that his family were all in bed. A single light shone from a window on the third floor where Lena, the cook, slept. "Maybe we can force a window," suggested Hugh. "You can open the door from the inside, can't you?" "Oh, yes," said Bob. "Let's try a window anyway." They went around the corner of the garage and the first window they tried yielded immediately. A moment later both boys had clambered inside, and presently Bob found the electric light button. As the light flooded the garage Heinrich's angora cat rose sleepily from the tonneau of the automobile and stretched himself. A cloth covering over the parrot's cage kept that garrulous bird quiet. Percy lay stretched out in the water which filled his tub. "The dog must be out with Heinrich," said Bob.