One Step Too Far — John Russell Fearn

Claire Escott had ignored her father's warning against involvement with her fiance, Mark Rowland. However, she little realized the extent of the scientist's corroding ambition. And it was not long after their marriage that Rowland's ruthless pursuit of a scientific empire encompassed a horrifying murder. But that was only the start of things. Mark's scientific genius and obsessive ambition to go one step further eventually led to mass destruction - and the ultimate sacrifice...