“I heard him,” interrupted Tom.  “Yes, I know a Mr. Swift;” but Tom, with a sudden resolve, and one he could hardly explain, decided that, for the present, he would not betray his own identity.

“Ask him if Mr. Swift is an inventor.”  Once more the unseen person spoke in the voice Tom was trying vainly to recall.

“Yes, he is an inventor,” was the youth’s answer.

“Do you know much about him?  What are his habits?  Does he live near his workshops?  Does he keep many servants?  Does he—­”

The unseen questioner suddenly parted the side curtains and peered out at Tom, who stood in the muddy road, close to the automobile.  At that moment there came a bright flash of lightning, illuminating not only Tom’s face, but that of his questioner as well.  And at the sight Tom started, no less than did the man.  For Tom had recognized him as one of the three mysterious persons in the restaurant, and as for the man, he had also recognized Tom.

“Ah—­er—­um—­is—­Why, it’s you, isn’t it?” cried the questioner, and he thrust his head farther out from between the curtains.  “My, what a storm!” he exclaimed as the rain increased.  “So you know Mr. Swift, eh?  I saw you to-day in Mansburg, I think.  I have a good memory for faces.  Do you work for Mr. Swift?  If you do I may be able to—­”

“I’m Tom Swift, son of Mr. Barton Swift,” said Tom as quietly as he could.

“Tom Swift!  His son!” cried the man, and he seemed much agitated.  “Why, I thought—­that is, Morse said—­Simpson, hurry back to Mansburg!” and with that, taking no more notice of Tom, the man in the auto hastily drew the curtains together.

The chauffeur threw in the gears and swung the ponderous machine to one side.  The road was wide, and he made the turn skilfully.  A moment later the car was speeding back the way it had come, leaving Tom standing on the highway, alone in the mud and darkness, with the rain pouring down in torrents.

CHAPTER VII.

OFF ON A SPIN

Tom’s first impulse was to run after the automobile, the red tail-light of which glowed through the blackness like a ruby eye.  Then he realized that it was going from him at such a swift pace that it would be impossible to get near it, even if his bicycle was in working order.

“But if I had my motor-cycle I’d catch up to them,” he murmured.  “As it is, I must hurry home and tell dad.  This is another link in the queer chain that seems to be winding around us.  I wonder who that man was, and what he wanted by asking so many personal questions about dad?”

Trundling his wheel before him, with the chain dangling from the handle-bar, Tom splashed on through the mud and rain.  It was a lonesome, weary walk, tired as he was with the happenings of the day, and the young inventor breathed a sigh of thankfulness as the lights of his home shone out in the mist of the storm.  As he tramped up the steps of the side porch, his wheel bumping along ahead of him, a door was thrown open.