as he left, he announced that he intended to keep watch of the yacht during the early part of the night.

As it grew dusk, Madge prepared supper. Enid tried to help but could not keep her mind on what she was doing. After wiping the dishes, they wrapped themselves in steamer rugs and sat out on deck. For a long time they watched the twinkling shore lights. Once they heard the drone of an airplane overhead and imagined that it might be Rex.

In spite of their declaration to the contrary, the girls were not entirely easy in their minds. The very quiet of the yacht was disturbing. The night had closed in dark and threatening; black shadows lurked everywhere.

At ten o’clock they decided to turn in. Enid was so tired and worn out that she dropped asleep almost at once. Madge rolled and tossed for the better part of an hour. At last, she too dozed off.

She had no way of knowing how long she slept, but suddenly she found herself sitting upright in bed. What had awakened her? She glanced at her companion. Enid was sleeping peacefully.

After a moment, she sank back against the pillows, but scarcely had her eyes closed than she was startled by a peculiar sound. A boat was scraping against the side of the yacht!

Cold shivers ran over her body and she resisted the temptation to burrow down beneath the blankets.

“Enid, wake up!” she whispered, shaking her chum roughly by the arm.

Enid stirred and as she was shaken again, opened her eyes.

“What’s the matter?” she murmured drowsily.

“Hush!” Madge warned in an undertone. There was no need to say more for by this time Enid had fully awakened.

Both girls listened intently. Footsteps could be heard plainly on the deck. Someone had boarded the boat!

“Perhaps it’s one of the sailors,” Enid whispered, but her voice quavered.

“We must see!” Madge returned. “Come on!”

Enid gripped her hand and tried to hold her back. “Oh, I’m afraid!”

“Then I’ll go alone.”

But Enid would not stay behind. As Madge quietly slipped out of bed, she was close beside her. Clinging together, they crept to the door and listened. They could hear the footsteps more distinctly now.

Madge opened the cabin door a crack and peered out. At first she saw nothing, then as her eyes became more accustomed to the dark, she beheld the figure of a man. She saw him pause, look searchingly about and then swiftly enter Mr. Burnett’s cabin.

For an instant she was too startled to move. Then she whispered into her chum’s ear.

“Now is our chance! We must steal out there and lock him in!”

CHAPTER VII
A Motor Boat Chase

Madge quietly opened the door and moved stealthily toward Mr. Burnett’s cabin. Enid, terrified at the thought of remaining behind, followed.

They stole softly along the deck, every muscle tensed for the unexpected. Madge stepped over a coil of rope in her path and too late turned to warn her chum. Enid failed to see it. She stumbled and fell flat on the deck, letting out a sharp exclamation.

Before she could regain her feet, a figure darted from Mr. Burnett’s cabin. He went over the railing like a flash and was lost to view.

“Oh, we mustn’t let him get away!” Madge cried.

She jerked Enid to her feet and they reached the railing just in time to see a motor boat speed away from the yacht.

“Enid, can you run your father’s motor boat?” she demanded.

“Yes, but——”

“Then come on! Our only chance of tracing your father is to follow this man!”

Rex had filled the tank of the motor boat that afternoon, but it required several minutes before Enid had the engine going. Madge cast off and they moved away from the yacht.

“To the right!” she directed. “I saw him head that way.”

Enid swung the wheel and they made for the open water. The boat rapidly gathered speed until the sea split from under her prow in huge waves.

“Can you see him, Madge?”

“Dead ahead. He has the engine muffled.”

“Then we’ll lose him if we’re not careful.”

“Can’t you go faster?”

Enid shook her head.

For a few minutes longer they kept the boat in sight but it was increasingly apparent that they were running a losing race. The man they were following knew the channels and his boat was fast. Soon he was swallowed by the night.

After it was evident that they had lost him, Enid stopped the engine. They listened for a few minutes but there was no sound of a motor boat.

“I guess we may as well turn back!” Madge said in disgust.

“It was all my fault,” Enid grieved. “Of course, I had to stumble over that old rope!”

“It wasn’t your fault, honey,” Madge comforted. “It was just a bad break of luck.”

Enid was silent as they slowly steered back toward The Flora. Madge too, was occupied with her own thoughts. She wondered what could be the meaning of the midnight visit. Had the prowler come for the purpose of ransacking the cabin or was it possible that he had brought some message?

The girls were thoroughly chilled by the night air before they reached the yacht. Yet, the adventure had made them far too nervous to even consider going back to bed. After lighting nearly all of the lamps, they screwed up their courage and entered Mr. Burnett’s cabin. A hasty glance about assured them that nothing had been touched.

“I guess he didn’t have time to do any damage,” Enid declared. “What do you suppose brought him here tonight?”

“I wish I knew.”

“Well, I think Rex was right about staying here alone. It was a terribly foolish thing to do. I’ll not spend another night here without a guard.”

After a time they settled themselves in deck chairs, and there, snuggled down under steamer rugs, they spent the remainder of the night. For some reason they felt safer out in the open where they could see any boat that might approach. Occasionally, they dozed off, but for the most part they maintained a vigilant watch.

At dawn they stretched their cramped limbs and went to Enid’s cabin to freshen up. Hot coffee revived their spirits and strengthened their morale. As the sun beat down upon the deck it was difficult for them to believe that they had spent such a harrowing night.

“We must report to the police immediately,” Madge advised. “They may attach special significance to what happened during the night.”

Soon after breakfast, Mr. Burnett’s cook and three sailors appeared upon the scene, and after she had given them orders for the day, Enid was ready to leave.

“It’s a relief to know someone will be at the yacht while we’re gone,” she said to Madge as they drove away in the motor boat. “Jose the cook was quite broken up to hear about Father. And the sailors too have always liked him.”

At the police station, the girls related the happenings of the night. While the authorities offered no comment other than to ask a few questions, it was plain that the incident puzzled them. Enid had hoped the police would have good news to report, but seemingly, the case was at a standstill.

“There’s very little we can do until some communication is received from the kidnappers,” Mr. Randall told her. “Rest assured a demand for ransom will be made soon.”

“But more than twenty-four hours has elapsed already,” Enid protested. “If those men were after money I should have thought they would have left a note behind at the time of the kidnapping.”