"Yes, he got it honestly, of course," said Slim. "The money was paid him by a man who owed it to him. But dad couldn't say anything about it because he promised not to. This man owed two other men besides my father, and those debts should have been paid first. He was afraid the others would sue him if they heard he had paid dad, so he made my father promise to say nothing. And when my dad makes a promise he keeps it." The boys looked at one another. To tell the truth, few of them had thought of the affair of the nine hundred dollars, but now that it was recalled to them they realized that here was the final angle of the Tower Mansion mystery cleared up at last. They cheered Slim to the echo, they pounded on the table with their knives, and when Hurd Applegate came in to see what the racket was about they gave him three cheers and made him sit at the head of the table. And that ended the affair of Tower Mansion, but it did not end the career of the Hardy boys as amateur detectives. They were soon to be called on to help solve another mystery, and the story of their adventures in this case will be told in the next volume of this series, entitled "The Hardy Boys: The House on the Cliff." "Speech! Speech!" the boys were shouting to Hurd Applegate. The old stamp collector got up, smiling. "It's been a long time since there's been a crowd of boys in Tower Mansion," he said. "I've been in danger of forgetting that I was ever young once myself. So I want you to come back--often. I want you to know that Tower Mansion is always open to the Hardy boys and their chums." The Hardy boys looked at one another, as the crowd about the table broke into a yell of delight. "He's a pretty good old scout after all, isn't he?" said Frank. "You bet he is," replied his brother. THE END * * * * * MYSTERY STORIES FOR BOYS By FRANKLIN W. DIXON THE HARDY BOYS: THE TOWER TREASURE THE HARDY BOYS: THE HOUSE ON THE CLIFF THE HARDY BOYS: THE SECRET OF THE OLD MILL (Other Volumes in Preparation)