Murder and chicanery stalk St. Vincent Halfhyde as he is given the unwelcome task of taking the old square-rigged ship Glen Hallandale on government service from Devonport dockyard to Cape Town. His "cargo" consists of a large draft of unruly, dangerous convicts from Dartmoor Prison, volunteers for the fight against the Boers in South Africa-volunteers who travel in chain gangs and under strong escort or armed warders in Halfhyde's hastily converted holds. The voyage proves a turbulent one through bad weather and the temper-inflaming heat and stickiness of the Doldrums. Conditions in the hold are appalling and the chain gangs are stirred to riot by their murderous ringleaders. Vicious fighting develops when a party from a mysterious steam yacht attempts to board the Glen Hallandale and seeks to make contact with a gentleman convict. And then there is the matter of the gold bullion hidden aboard . . .