"Then come to headquarters at once," said Old King Brady, as they left the cars.

They met the chief in his office and he smiled pleasantly, and asked:

"Well, where have you two been keeping yourselves hidden during the past week? I haven't seen or heard from you lately."

The Bradys told him what they had been doing.

He listened attentively, with a grave look upon his face, while they were giving him the facts, and said when they finished:

"Then that murder mystery was too much for you, and you went beyond your depth trying to solve it, eh? Well, it's just as well you let it drop."

"Anything new going on?"

"Yes. Something relating to your mail robbery case."

"Indeed! What was it?"

"Oliver Dalton has disappeared."

"Where to?"

"n.o.body seems to know."

"That is very strange."

"You had better go up to his house and get the particulars from his daughter. She is frantic to find her father. Some points might be gained in the broker's Broad street office."

"We'll follow your advice, sir," said Old King Brady.

The chief did not seem to have many facts in relation to the case, so the detectives finally left him.

Going to the broker's office, they found it occupied by half a dozen clerks.

Having asked for Mr. Dalton, the office boy said to them:

"You'd better see Mr. Mason about that matter, sir."

"Is the broker's nephew in?" asked Harry.

"Yes. He's the boss here now. Got your card?"

Harry handed him a business card and he carried it into a private office in the rear. A few minutes later he came out, with a smile on his face, and said to the detectives:

"Mr. Mason says for you to come in."

He ushered the Bradys into the private office and they there beheld Ronald Mason, the broker's nephew, sitting at his desk.

About thirty years of age, his tall, thin figure clad in stylish clothing, Ronald Mason was a clean-shaven individual, with hard features.

He had cold, gray eyes, and a haughty, overbearing appearance.

When the detectives came in, they saw him bending a queer, searching look at them, and he then asked in low tones:

"Well, gentlemen, what can I do for you to-day?"

Neither of the detectives were favorably impressed with his appearance.

They had seen the odd look he gave them, and set him down for a tricky and dangerous man to deal with.

Old King Brady took him in hand by saying:

"You are Mr. Mason, I believe?"

"That is my name, Mr. Brady."

"We have heard that your uncle has mysteriously disappeared."

"That's correct. We've reported the matter to the police. I presume you are here to get information about him, ain't you?"

"Yes. What do you know about the case?"

"Simply this: Last Monday he left this office at five o'clock and proceeded to the Union Club. At about eight o'clock, after his dinner, a telegram was brought in to him. He showed some agitation, put on his hat, took his umbrella and hastily departed. No one seems to know where he went. That was the last we've seen or heard of him since. We informed the police and nothing has yet come of it."

"Did he have any domestic or business trouble?"

"None that I'm aware of."

"Ever speak of suicide?"

Mason a.s.sumed a very mysterious air, bent near the detectives and replied:

"Yes! Several times. And I fear he has kept his threat at last."

The Bradys were startled at this unexpected reply.

CHAPTER V.

THE PICTURE ON THE WALL.

Ronald Mason was keenly watching the effect his words produced upon the detectives, and he noted their looks of astonishment.

When Old King Brady recovered from the shock, he demanded:

"Can you tell me why your uncle contemplated suicide?"