"Some one came and got it!" exclaimed Tom, when it was certain that the machine had vanished.
"Who was it?" came from Ned.
"Hard to say. But I guess we weren't wrong, Ned, in suspecting that we were being spied upon by unseen eyes in that old house."
"I'm forced to believe that."
"While some watched us inside, to make sure we wouldn't come out and interrupt the theft, others stole the House," declared Tom.
"Looks so," commented Ned. "Gee, but this is tough luck! What are we going to do now?"
"We've got to hit the trail, of course, and see if we can't get it back," was Tom Swift's prompt answer.
Though they were hungry and tired, the two young men did not hesitate. In fact, they could not. Much depended on prompt action, for the House on Wheels could not long have been taken away. Luckily Tom and Ned had on rubber boots and rain coats, and their little electric flashlights enabled them to see the trail. Without them they would have been at a great disadvantage.
But with these gleams, flashing occasionally so as not to wear out the batteries too fast, the two first made sure where the big auto had stood and then began to trail it.
"They first swung around in a half circle and then went off this way," said Tom, pointing to the peculiar marks in the mud left by the tires of the House on Wheels. They were tires especially made for heavy duty and marked with ridges designed to prevent skidding, so the trail was easily followed, particularly as the wet ground took a deep impression.