"You remember the day we were at the old mill?"
"I'll say I do! Those fellows wouldn't let me dry my clothes in the mill after I'd fished that precious kid out of the water."
"But one of them offered us a reward, didn't he?"
"Oh, well—you can't take a reward for that."
"That isn't what I'm getting at. Do you remember how the other man grabbed the bills out of his hand and turned his back to us?"
"Sure! He said he wanted to see if they were fives or ones. But it was rather funny that he turned his back to us. I thought so at the time. Still, he offered the money to us again."
"But was it the same money?"
Joe was silent. The idea had not occurred to him before.
"Do you mean," he said at last, "that perhaps the fellow changed the bills while he had his back turned?"
"Exactly."