This is the third Dr Nikola book in a series of five written by Guy Boothby. The main character is Gilbert Pennethorne a man whom "Lady luck" has deserted. A number of commercial failures, estrangement from his family, Unsuccessful gold prospecting in Australia and finally having the location of one of the richest undiscovered gold mines in the world stolen from him by a man whom he classifies as his worst enemy. This tips him over the edge of normal reason, such that his desire for revenge is all consuming. This gives Dr Nikola, ever the master manipulator, the opportunity to utilise Pennethorne’s hatred to his financial advantage by convincing him to murder Richard Bartrand the thief of the mine (now a multi millionaire) in a devilish and bizarre mechanical method. After the deed is done, Pennethorne, essentially a decent man, realises his serious error in being an accomplice to Nikola and flees the country en route for South Africa. Thus his adventures at sea and on land begin and his true nature is divulged. (Peter Keeble)