Bob sighed.
"Isn't there some way that this young girl can be warned about the dangers she is running into? It's terrible to think of a thing like this threatening any girl of good family, or any other family for that matter."
"You must simply warn her sister and have her watch the younger girl like a hawk."
MacFarland cleaned out his pipe with a scalpel knife, and put in another charge of tobacco.
He puffed a blue cloud before Bob had replied.
"I wish there were some way I could get co-operation on this. I'm going to hunt these fellows down, Doc. But it seems to me that the authorities in this city should help along."
"They are helping along. The District Attorney has sent up gangster after gangster; but it's like a quicksand, Burke—new rascals seem to slide in as fast as you shovel out the old ones."
"I have the advantage now that they don't know who is looking after Lorna," said Bobbie. "But it was a hard job getting them off my track."
"That was good detective work—as good as I've heard of," said the doctor. "You just keep shy now. Don't get into more gun fights and fist scraps for a few days, and you'll get something on them again. You know your catching them last night was just part of a general law about crime. The criminal always gives himself away in some little, careless manner that hardly looks worth while worrying about. Those two fellows never dreamed of your following them—they let the name of the restaurant slip out, and probably forgot about it the next minute. And Jimmie the Monk has given you a clue to work on, to find out the connection. Keep up your work—but keep a bullet-proof skin for a while."
Bob started toward the door. A new idea came to him.