In the "_The Submarine Boys' Trial Trip_" was related how Jack Benson solved the problem of leaving a submarine boat when it lay on the ocean's bottom, and also the trick of entering that submerged boat again, after diving from the surface of the water. The attempt of shrewd business men to secure control of the new submarine boat company was also described, together with the manner in which the submarine boys outwitted them. Through a successful trial trip, and Captain Jack's ingenious ways of arousing public interest, the government was forced to buy the "Pollard," as the first of the submarines was named. In "_The Submarine Boys and the Middies_" was narrated how the submarine boys secured the prize detail of going to the Naval Academy at Annapolis as temporary instructors in submarine boating. Many startling adventures, and some humorous ones, were related in that volume. Then in "_The Submarine Boys and the Spies_" was shown how the young men successfully foiled the efforts of spies of foreign governments to learn the secrets of the Pollard craft. In "The Submarine Boys' Lightning Cruise" the adventures of these clever, enterprising boys were carried further. In this book, was told how the boys were trained in the handling of the actual torpedo of, warfare. The Pollard boats, "Benson" and "Hastings" were entered in official government tests in which the submarine craft of several other makes competed. The desperate lengths to which the nearest rival of the Pollards went in order to win were told with startling accuracy. The result of all these tests was that the Pollard company received from the Navy Department an order for eighteen submarine torpedo boats, the "Benson" and the "Hastings" being accepted as the first two boats on that order. By the time the present narrative opens it was near the first of May. Over at the shipyard, where facilities had been greatly increased, two of the submarines had lately been finished, and four more were under way in long construction sheds. Work on the government's order was being rushed as fast as could be done while keeping up the Pollard standards, of high-class work. Of late Jack and his young friends, though their pay went on, had little work to do. Whenever a new boat was completed it was the task of the submarine boys to take her out to sea and put her through all manner of tests in order to determine her fitness. But there were days and days when the submarine boys had naught to do but enjoy themselves as their fancy dictated. "Shall we sit down here?" asked Jack, as he and the tall German entered the hotel office. Jabez Holt stood behind the desk, bent over the register, on which the Professor's name had been the only new one in a week. The old landlord pretended to be busy, but he was covertly watching and listening. "Sit here?" repeated Professor Radberg. "Ach, no! Come along with me."