Marcia Angell gets at the major plot flaw in the Constant Gardner: "Yet the story is based on the premise that a pharmaceutical company would be so threatened by disclosures of its activities that it would have someone killed. That is what is fantasy. In fact, many of the practices that so horrified le Carré's heroine are fairly standard and generally well known and accepted. They seldom provoke outrage, let alone murder. A company like KDH would not kill someone like Tessa even if it were willing to do so; it wouldn't have to. Her concerns would have seemed isolated and futile, and the companies would hardly have taken notice of them."
Good one. The rest of the review is also worth reading.