[Illustration: fifth instalment]
BY PERCY F. WESTERMAN
GERALD TREGARTHEN, sub-lieutenant of H.M.S. Calder, being on leave, sails from Poole with his old school-chum Jack Stockton on board the latter's yacht Playmate. In mid-Channel the yacht is run down; the two friends are rescued, and find themselves on board a mysterious cruiser—the Olive Branch—commanded by Captain Brookes. Finding that Tregarthen is a British naval officer, Captain Brookes announces his intention of keeping him on board, and, after due deliberation, Gerald decides to fall in with the captain's plans, as far as his sense of loyalty will permit.
Tregarthen is initiated into the secrets of the Olive Branch, including that of the deadly ZZ-rays—an irresistible charge of electricity whereby the destruction of a hostile ship can be made at will. Captain Brookes also explains that by the power at his command he hopes to make war so terrible that no nation will venture to declare war; thus universal peace will be assured. During the voyage south a German "tramp" is boarded for the recovery of some plans which had been stolen by a deserter, and for this action the Olive Branch is branded as a pirate.
Hostilities break out between Chili and Peru, and Captain Brookes determines to intervene. The Olive Branch is damaged by a mine, and while undergoing repairs is trapped by a British squadron. Captain Brookes is handicapped by a vow never to fire on a British vessel.
By the aid of the Z-rays, however, the Olive Branch escapes, though not without sustaining injury. The vessel puts into a creek in the Patagonian coast for repairs. A number of blacks which are encountered at first appear friendly, but afterwards prove treacherous, and to cower them Captain Brookes utterly destroys, by means of the ZZ-rays, a huge rock regarded by the natives as the home of their god of war. Later the captain receives a message which, without disclosing particulars, he tells Tregarthen is to the utmost urgency, and involves immediate action.