The Beast-Jewel of Mars - Leigh Douglass BRACKETT

Following the suspicious death of his girlfriend, Captain Burk Winters sets off down the dangerous path of a Martian vice called 'Shanga'-- the Going Back. What starts out as an effort to rescue Jill Leeland will pit the former starship captain against the dark underbelly of the canal cities, conspiracies of greed and, above all, the vengeance of a planet that will not bow to economic conquest without a fight. - Summary by EVKesserich