A contemporary review (otherwise negative) offers the following synopsis:
IN 'Tropic Equations' (The Macquarie Head Press, Sydney, 6s net), Mr. Don Gordon has essayed a parallel between the native mind and the white. His backgrounds are New Guinea and Sydney, and he tells the story of Donald Fraser, a trader, his wife Ethel and their adventures and amours. Ethel is on a recuperative trip to Sydney and life in the Hotel Australia transforms her into something of a social butterfly. Donald pursues his gloomy path back in New Guinea, where there is Another Woman, and there is considerable hotch potch about native rites so dear to writers of tropic lands. Apparently Donald was a witch doctor in his spare time.
'An Island Story', Daily News [Perth], 20 January 1934, p.16.