"We can't stop to talk, fellows," declared Bob, hastily; "Sam and I will meet you this evening. No use to make any kick," he added, as Dick began to object.
Then, before the other Ramblers could add a word, he was off, with Sam at his heels.
"As I live, I'm afraid he has slipped away from us," exclaimed Sam, who was full of enthusiasm at the new rôle he was playing.
"No! I see him, passing that white building over there," cried Bob. "Now, Sam, we must be very cautious. One little mistake might spoil the whole business."
The two separated, taking different sides of the street.
Bob found that shadowing was not as easy as he had supposed it to be. To keep Nat in view, and himself out of sight, proved a difficult task. Once, owing to groups of people and passing vehicles, the trail was lost entirely.
But Sam Randall's sharp eyes had been used to advantage, and with a wave of the hand, he put Bob on the right track again.
"My gracious!" muttered the lad; "he's just going to the post-office, after all. Perhaps we're having a wild goose chase. Yes," he added, a few moments later, "that's where he is bound."
Nat turned into the building, while Sam Randall rejoined his companion.
"Think we got left this time?" observed Sam.