Lieutenant Halfhyde, RN, is ordered to assist in the capture of a British traitor who carries secret drawing of planned British naval consturction to give to the Germans. Joined by a Scotland Yard detective witha an arrest warrant, they set out for the wilds of a South Aftican river to hunt down their prey.

Royal Navy Lieutenant St Vincent Halfhyde is in command of a torpedo-boat, part of a flotilla sent to rescue a British sailing-ship, unlawfully detained by the Russians. Cutting out the sailing-ship from amidst the Russian fleet and sneaking her back through the Narrows under the deadly batteries of the Turks and the Russians is the easy part.

In Andalusia, Lieutenant St Vincent Halfhyde is sent by the unpredictable Captain Watkiss on a secret mission ashore: to aid the Queen's Messenger who is being pursued by nefarious Spanish agents. But when Halfhyde discovers a plot to kill Queen Victoria herself, the stakes are raised. Now he and the rest of his flotilla must face down the Spanish Navy and get the Messenger back to Britain with vital information.

The old iron-clad Meridian steams south on her last journey under the British flag, on route to her new home in the Chilean Navy. Using the transfer of the ship as cover, Halfhyde and Watkiss are on a covert operation to protect British interests in South America from the encroaching Germans. Soon Halfhyde has an added mission: he must help a detective from the Metropolitan Police track down and intercept a traitorous civil servant who has escaped from prison and is on the run for South America.

Halfhyde again proves to be a calienat sailor, and his story is fine and thrilling reading.

When the Russians establish a naval presence in the Bight of Benin off West Africa, the Admiralty is worried. Will the Russians threaten British interest? Lieutenant St. Vincent Halfhyde is sent to investigate. Outpsoken and independent, Halfhyde is soon captured by the Russians.

Royal Navy Lieutenant St Vincent Halfhyde is assigned a second in command of the heavy cruiser Viceroy and ordered to a volcanic island that has recently surfaced in the north Pacific. The Admiralty hopes to claim the island for the Crown and establish an outpost there, but the hostile Russians have other ideas and the wily Japanese are prepared to carry out their own agenda.