"They're in the strong room; they've found the treasure!" His words echoed the length of the _S-18_ and a shout went up from the crew. "Charlie Gill says someone must have made an attempt to get the treasure out before the Southern Queen sunk. The door of the strong room is open and several of the steel chests are outside the door. They're bringing them out now." Minutes passed as the divers, each carrying a steel chest, made their way out of the interior of the Southern Queen and back along the side of the _S-18_. Tim's keen eyes were the first to see them. Russ Graham was ahead, his arms wrapped around a rusty steel chest. Close behind came Charlie Gill, with a similar chest in his arms. They deposited these in the diving compartment and waved to the men watching them through the quartz windows. Then they were beyond the circle of light, seeking more treasure in the hold of the old tramp steamer. "How long can they remain down at this depth?" Tim asked the commander. "Not long. The pressure is too great, but Charlie and Russ are the best divers in the world. They'll stick as long as they dare." Another and still another trip was made by the divers into the hold of the Southern Queen. The pile of steel boxes mounted. Six were stacked together. There were only two more. Then the job would be done. Ike Green came running forward from his radio room. "Something mighty funny is happening near us," he told Commander Ford. "My microphones are picking up all kinds of noises within the last two minutes." A slight tremor ran through the hull of the _S-18_. Commander Ford shouted into the telephone. "Charlie! Russ! Return at once! Don't attempt to bring out the rest of the gold. Hurry!" There was another slight movement. Men looked at each other in amazement and fear. Out of the darkness came the divers. Charlie Gill had a treasure chest. Russ Graham's arms were empty. Into the protection of their diving compartment they stumbled. With a clang the outer doors snapped shut. "We're getting back to the surface as soon as possible and away from the hull of the Southern Queen at once," snapped Commander Ford. Men hastened back to their posts, but before they could get there, the _S-18_ moved again. From the outside there was the sound of metal scraping against metal. Then silence. They took their places, diving planes were adjusted for the ascent and orders flew from Commander Ford's lips. The electric motors purred smoothly. Compressed air hissed into the ballast tanks, blowing the water out to lighten the submarine. Tim, watching the depth gauge, waited for the needle to move. Earl Bell came into the control room. "You might as well shut off the motors and save the air," he said dully. "That last shock put a part of the hull of the Southern Queen on top of us. We're trapped." CHAPTER TWENTY-THREE Desperate Hours