"Do you think we're going to be in for trouble before we get through?" Tim asked as he watched the sharp bow of the _S-18_ cut through the gentle swells. "Commander Ford told me this morning that Sladek had rounded up about the prize gang of cutthroats on the New York waterfront. You'll get all of the excitement you want before this shindig ends." "Just give me time enough to get aloft in the plane and I'll be ready for anything that comes along," said Tim, nodding toward the trim seaplane lashed securely on the forward deck. Mess was served in relays that noon and shortly after that Tim sighted the seaplane winging up from the south. "Company coming," he informed Pat, who was back in the conning tower. Commander Ford was summoned and they watched the approach of the fast craft. The plane was flying high, but as it neared the _S-18_, the pilot put it into a dive. "That fellow knows how to handle a plane," said Tim, half to himself. The seaplane came out of the dive at a thousand feet and circled the _S-18_. "The answer to that is plain," said Commander Ford grimly. "That's Sladek's ship and it won't be long until his dirty old tramp steamer is on our trail again." The seaplane winged away again and in less than two hours they saw a smudge of smoke on the horizon. Before sundown the tramp steamer, the _Iron Mate_, was riding a half mile off their port bow. "There's no use trying to sneak away from them now," said the commander. "When we get out of Key West and head across the Caribbean we'll find some way to give them the slip." Down the east coast the _S-18_ made its leisurely way with the _Iron Mate_ a constant companion. The sky was clearer, the air warmer, as they neared the southern tip of Florida and nosed into the harbor at Key West. The Iron Mate stood out to sea, waiting for the return of the _S-18_, for Sladek was taking no chances on getting into trouble with federal officials. The _S-18_ replenished its fuel oil tanks, fresh supplies were taken aboard, and the crew stretched its legs before the voyage into the Caribbean. Pat and Tim strolled along the wharfs. It was a picturesque city and they enjoyed the walk at the sunset hour. A small boat was coming in from the sea. They watched it curiously for the men at the oars were particularly vicious looking. "I wouldn't want to meet them on a dark night," said Pat. When they returned to the _S-18_, Commander Ford divulged his plans for eluding the _Iron Mate_ and its crew of cutthroats. "Tim," he said, "we'll hoist your seaplane overboard at once. Then we'll slip out of the harbor and run submerged until we are well away from the coast. You fool around here all day tomorrow. The next morning hop early and rejoin us at this joint." The commander indicated a spot in the Caribbean approximately two hundred miles west of Key West.