The Hardy boys walked along the street in silence. They realized that the situation was urgent, but although they racked their brains trying to think of some way in which to prevent Chief Collig and Detective Smuff from catching the train, it seemed hopeless. "Let's round up the gang," suggested Joe. "Perhaps they can think of something." "The gang" consisted of the boys who had been with Frank and Joe the day they held the picnic in the woods. There was, of course, Chet Morton. Besides him were Allen Hooper, otherwise known as "Biff", because of his passion for boxing, Jerry Gilroy, Phil Cohen and Tony Prito, all students at the Bayport high school. They were usually to be found on the school campus after hours, playing ball, and there the Hardy boys soon located them. The game was just breaking up. "Pikers," grinned Chet Morton when he saw the Hardy boys approaching. "You wouldn't play ball when we asked you to, and now you come around when the game's all over." "We had something more important on our minds," replied Frank. "We need your help." "What's the mattah?" asked Tony Prito. Tony was the son of a prosperous Italian building contractor, but he had not yet been in America long enough to talk the language without an accent, and his attempts were frequently the cause of much amusement to his companions. He was quick and good-natured, however, and laughed as much at his own errors as any one else did. "Chief Collig and Detective Smuff are butting into one of dad's cases," said Frank. "We can't tell you much more about it than that. But the whole thing is that they mustn't catch the seven o'clock train." "What do you want us to do?" asked Biff Hooper. "Blow up the bridge?" "We might lock Collig and Smuff in one of their own cells," suggested Phil Cohen. "And get locked in ourselves," added Jerry Gilroy. "Be sensible. Are you serious about this, Frank?" "Absolutely. If those two catch that train dad's case will be ruined. And I don't mind telling you it has something to do with Perry Robinson." Chet Morton whistled. "Ah, ha! I see now. The Tower affair. In that case, we'll see to it that the seven o'clock train leaves here without our worthy chief and his equally worthy--although dumb--detective." He hated Smuff, for the sleuth had once or twice tried to arrest the boys for bathing in a forbidden section of the bay. "There is only one question left," said Phil solemnly. "And what is that?" "How to keep them from getting on the train." "Get your brains to work, fellows--if you have any," ordered Jerry Gilroy. "Let's figure out a plan." A dozen plans were suggested, each wilder than the one before. Biff Hooper was in favor of kidnapping the chief and his detective, binding them hand and foot and setting them adrift in the bay in an open boat. Phil Cohen suggested putting the chief's watch an hour ahead. That plan, as Frank observed, would have been a good one but for the little difficulty of laying hands on the watch.