"A Watch-dog of the North Sea: A Naval Story of the Great War" by Percy F. Westerman is a naval fiction novel likely written during the early 20th century amidst World War I. The book centers on the adventures of the crew aboard H.M.S. "Pompey," an armoured cruiser, particularly focusing on characters like Assistant Paymaster Eric Greenwood and his friend Ronald Tressidar, while combining action, camaraderie, and the harsh realities of war at sea. The opening portion of the story introduces Eric Greenwood as he completes his duties aboard the cruiser and looks forward to receiving letters from home. As he interacts with fellow officers, the atmosphere aboard the ship is interrupted when a torpedo narrowly misses them, revealing the constant threat of enemy submarines. The narrative then shifts to the perspective of a new stoker, James Jorkler, whose ulterior motives foreshadow danger, hinting at a conspiracy against the vessel and its crew. This sets the stage for tension and intrigue as Greenwood's father, Mr. Greenwood, uncovers significant information regarding a secret petrol depot that could pose serious implications for the war effort. The stage is thus set for action-packed developments ahead. (This is an automatically generated summary.)