Suddenly Joe gave a cry. "Look! Someone's been here recently."

His eye had fallen on something lying on the floor of the cave. He s.n.a.t.c.hed it up-a partially burned white envelope. Evidently the dampness had put out the flames.

"Frank!" Joe exclaimed, straightening the envelope and staring at it. "It's one from our house with a return name and address!"

His brother took one glance, and said tensely, "It must be the envelope you put the two hundred dollars in!"

"You mean this is that thief's hide-out?" Chet asked nervously. "Maybe he's one of the smugglers?"

Frank and Joe did not reply. Instead, they began a frantic search, thinking the two one-hundred-dollar bills might be cached away in the cave. They did not find them, but under a fallen stalact.i.te Chet pounced on another sc.r.a.p of paper.

109 "Hey! Here's something else, fellows!"

It was part of a half-burned letter typed on business stationery. The torn-off fragment bore the following lines: would advise you to get in on the ground floor while the stock shares can still be purchased cheaply. The mining deposit is a rich one and the company is bound to realize tremendous profits during the next few "I'll bet that thief uses his stolen money to buy stock," Chet guessed.

"Could be," Frank commented. "Chet, this is a real find. It could be our best clue so far to that burglar."

Joe mused aloud, "Typewriters all have distinguishing characteristics. If we can trace the machine this was written on, it may give us a real lead!"

"Do you think the burglar is part of some gang interested in the Hai Hauf" Hai Hauf" Chet asked. Chet asked.

"I wonder," Frank replied. "If so, they know this cave well. The sooner we get busy on this stock-letter clue the better. Let's go."

"Let's talk to Sam Radley about the case if he's back," Frank suggested as he started the convertible. "He's an expert on typewriter clues."

Sam Radley was Fenton Hardy's best operative. He had gone to Chicago recently to collect evidence needed in another case which Mr. Hardy was handling.

110 "Neat idea," Joe agreed.

Frank dropped Chet off at the farm, then drove home. He telephoned Radley and learned that the detective had flown in to Bayport late the previous day. He promised to come over to the Hardy house at four o'clock that afternoon.

In the meantime, the brothers made fingerprint tests on the two pieces of paper. Only their own prints were revealed!

"That burglar is a slick article," Joe remarked. "He must wear plastic finger tips!"

"It's not hard for me to believe that he's also the safecracker," said Frank thoughtfully.

When Sam Radley arrived, the boys briefed the wiry, sandy-haired detective on developments in their mystery to date. Then Frank showed him the torn sc.r.a.p of letter.

"You're a typewriter expert, Sam. Can you tell us what kind of machine this was written on?"

The operative studied the typewritten characters with a practiced eye, then nodded.

"This was done on a German-make machine, called the Zeus. Should be easy to trace. This particular style of type was used only on the first model which was imported to this country three years ago."

Radley asked to use the hall telephone and placed a call to the New York distributors for the Zeus typewriter. Within minutes he had the information he sought.

111 "They're sold locally through the Bayport Office Supply," Sam reported to the Hardys.

"Okay, let's go talk to them," Joe said.

Radley drove the boys downtown to the Bay-port Office Supply Company. In answer to their questions, the proprietor consulted his records and informed them that he had sold only four typewriters of that make and model.

"The Zeus is a fine machine," he said, "but it wasn't well known at that time-three years ago. I sold the four all in one batch to the Regent Hotel."

After thanking him, Radley and the two boys went to the hotel. Frank explained to the manager, Mr. Irwin, that they were working on a case and would like to see the four Zeus typewriters which the hotel had purchased three years before.

"Certainly," Mr. Irwin agreed. The manager led the three sleuths into the hotel's business office. Several women clerks were at work, typing or running accounting machines.

Radley, Frank, and Joe examined samples of typing from each of the three Zeus typewriters in the office, and compared them with the letter.

"The V and the T are both out of line in the letter and the tail of the 'e' is worn away,"

Sam observed. "None of these samples matches."

Frank turned to the manager. "We were told at the Bayport Office Supply Company that you 112 bought four four Zeus typewriters. May we see the other one?" Zeus typewriters. May we see the other one?"

"We had that one a.s.signed for the use of our guests," Irwin replied. "But I'm afraid you're out of luck so far as checking it goes."

"Why?" Joe asked.

"The typewriter," Mr. Irwin explained, "was stolen a month ago."

"Stolen!" the Hardys chorused.

The identical thought raced through the brothers' minds. Was the typewriter thief the same person who had stolen their two hundred dollars, Mr. Hardy's file on the Chameleon, and perhaps owned the cuff link lola had found?

CHAPTER XII.

The Vanishing Visitor.

frank suddenly snapped his fingers. "Maybe the typewriter was stolen by someone staying here," he said to the hotel manager. "May we look at the register?"

"Of course."

Mr. Irwin led the Hardys and Sam Radley downstairs to the lobby and requested the clerk at the desk to show them the registration book. Frank and Joe flipped back the pages and began checking the names of guests who had registered at the motel a month previous.

"Oh-oh!"

Joe gave a surprised gasp and pointed to a signature written with a flourish- Dr. Hubert Dr. Hubert E. Montrose. Frank was equally intrigued. Frank was equally intrigued.

"Find something?" the manager asked.

"An acquaintance of ours," Frank replied cau113 114 tiously. "We didn't know he'd ever lived at this hotel."

"Let me see." Mr. Irwin glanced at the name on the register. "Oh, yes. Dr. Montrose stayed here for a week or so when he first arrived in town." He looked at the brothers curiously, but they did not voice their suspicions.

Frank, instead, added nonchalantly, "Dr. Mont-rose found a house here in Bayport?"

Mr. Irwin nodded. "Yes, he's renting the old Varney mansion out on the Sh.o.r.e Road.

Quite a show place in its day, but now it's rather rundown."

The sleuths thanked the manager for his cooperation and left. As soon as the three were seated in the car, Sam asked, "Who's this fellow Montrose?"

"A doctor who just started practicing here in town," Frank explained. "Most of his patients seem to be elderly widows. Dr. Montrose advises them on financial as well as medical matters, and refers them to a friend of his who deals in stocks."

The detective grinned as Joe told how Aunt Gertrude had vowed to prove the doctor a swindler but had gone to sleep instead.

Sam pulled away from the curb and started for the Hardy house.

"This stock business is why I was interested in finding out where Dr. Montrose lives,"

Joe went on. "It's just possible he can help us locate the 115 person who wrote the stock-selling letter and even stole our money!"

"I see," said Sam. "And that man in turn might point out the thief."

"Exactly. Let's call on the doctor at his house after supper."

Sam Radley said he would not be able to go, but Frank and Joe determined to make the call, anyway. Sam had supper with Aunt Gertrude and the boys. Later, as the operative was leaving, Tony Prito stopped at the Hardys' to report on the day's boat trip to Rocky Isle.

He told Frank and Joe that the Hai Hau Hai Hau had carried six pa.s.sengers on each round trip. It had carried six pa.s.sengers on each round trip. It had been an enjoyable excursion, with smooth sailing both ways.

"Swell," Frank commented. "Joe and I were just going out to do a little sleuthing. Want to come along?"

"Sure. What's up?" After hearing the plan, he said, "Let's go!"

The three boys piled into the Hardys' convertible. Frank drove through the outskirts of town, then took the Sh.o.r.e Road. Their headlights slashed through the gathering dust.

By the time they reached the old Varney mansion it was nearly dark. The house stood on a wooded promontory overlooking Barmet Bay. Frank slowed the car as they neared their destination and stopped at the entrance to the grounds. A heavy chain barred the way.

116 "We'll have to hike in," he murmured.

The boys found a footpath, which wound amid trees and underbrush, fully screening their approach. On the boys' right, the hillside sloped down steeply toward a sandy beach.

Presently they came in sight of the mansion. Built many years before, the house was designed in ornate Victorian style with gabled roof and outjutting turrets. It was surrounded by large hemlock and cypress trees.

"Sort of a spooky-looking place," Joe remarked.

"You said it!" Tony agreed.

As if to confirm their words, an owl hooted mournfully from the trees.

"I think he heard you," Frank joked.

Most of the mansion's windows were hung with dilapidated shutters, but a single light gleamed through an unshuttered window on the first floor. Frank suggested that they knock on the rear door which was nearest. Apparently this part of the grounds had once been a formal garden, but it was now clogged with waist-high weeds and undergrowth.

"Take it easy," Frank advised.

But Joe, impetuous as usual, pressed forward without watching his step. Tripping on a vine, he went sprawling. He gave a slight groan.

"Hey! Hurt yourself?" Tony asked.

"Wrenched my shoulder a bit, I guess. Gave me a twinge-it'll ease up, though."

117 Joe got to his feet, and followed the others, this time with caution. A moment later all three froze as a figure ahead loomed out of the shadows at one side of the house.

Apparently he had come from the front, which faced the bay.

Tall and stooped, the figure glided away from the mansion, losing itself among the trees and shrubbery on the hillside. His rather furtive manner instantly aroused the boys'

suspicions.

"Let's go see what he's doing," Joe urged.

Tony asked if the doctor lived alone.

"He's supposed to, according to what Mrs. Witherspoon told Aunt Gertrude," Joe confided. "She says he has no relatives and no housekeeper."

"Maybe that man's a patient," Frank offered.

"Or a guard," Tony added.

Joe was unconvinced. "If he is, he won't mind talking to us. But if he's a burglar, Dr.

Montrose would thank us for nabbing him."

"You win," said Tony.

The trio moved forward quickly. Reaching the edge of the promontory, they could make out their quarry picking his way down the slope toward the bay.

"Easy does it, Joe," Frank warned, as his brother plowed ahead.

Fortunately, the hillside was covered with tall gra.s.s and scrub, which afforded good footing. The boys managed to descend without turning 118 their ankles or falling. As they reached the bottom, they could see the stooped man hurrying across the beach.

"We'd better speed up or we'll lose him," Joe exclaimed, as the man went up a hillock of rock and sand.

He looked back for a moment, then darted down the opposite side and was lost to view.

"He may leave in a boat," Joe remarked worriedly.

The boys sprinted forward. But by the time they reached the top of the hillock, the man was nowhere in sight.