The Isle of the Singing Trees was living up to its name that night. The tangled mat of underbrush came down close to the water's edge and from it came a mournful melody. Now and then a vagrant breeze, skipping through the tree tops, added a higher note and Tim shivered at the loneliness and the desolation. The lights of the _S-18_, a bare 200 yards from the shore, looked far away. He was glad when Pat's boat grated on the rocky beach. Pat also felt the weird atmosphere of the island. "It isn't healthy here," he said. "Let's get back to the _S-18_." Tim jumped into the boat and they pulled lustily toward the safety and comfort of the submarine. Men slept restlessly on the _S-18_ that night. Tomorrow they were going to the bottom of the bay. If fortune favored them, they would come back to the surface with a wealth of gold. Tim was as restless as any of them, turning and tumbling around in his narrow bunk. An hour before dawn he slipped out of his blankets, dressed, and went up on deck. Commander Ford was in the conning tower and Tim wondered whether he had slept any during the night. "I'm a little anxious about the Sea King," said the flying reporter. "I'd like to turn the searchlight on the beach." "Not right now," said the commander softly. "There are lights of some kind over to our left." Tim turned sharply. Low in the water, and far out, he caught the faint glow of lights. "The _Iron Mate_?" he asked breathlessly. "Perhaps. We'll have to wait until dawn to know the truth." "It may be some passing steamer." "These are dangerous waters. Regular traffic keeps away from this section of the coast." Tim watched the lights intently. They were barely moving, but it seemed as though they were coming nearer. There was a faint glow in the east when Commander Ford spoke again. "Go below and rout out the crew. Tell Joe Gartner I want arms issued to every man. As soon as that is done I want him up here for final instructions." Tim shot down the ladder into the control room, landing with a bang that resounded through the interior. He raced back to the crew's quarters. Men, only half awake, tumbled from their bunks. "Everyone out!" cried Tim. "Joe, you're to issue arms at once. Then Commander Ford wants to see you on deck." "Glory be," croaked Joe. "It must be the _Iron Mate_. Maybe I'll get a chance to unlimber my gun after all." They tumbled into their clothes and went forward where Joe issued ammunition belts and revolvers. A stack of rifles was placed in a special rack in the control room with a box of ammunition beside them. The _S-18_ was getting ready for trouble. On deck Joe Gartner tore the tarpaulin off the four inch gun. From the depths of the _S-18_ a half dozen shells were brought on deck and the gun was trained on the cluster of lights.