The Constant Gardener by British author John le Carré was originally published in 2001 and made into a feature film in 2005. The novel centers on British diplomat Justin Quayle, stationed in Nairobi, Kenya, whose activist wife, Tessa, is murdered. Believing there is more to the murder than what the police are letting on, Justin takes it upon himself to uncover the truth, unraveling an international conspiracy involving corrupt bureaucracy and pharmaceutical money in the process. The plot of the novel is loosely based on a series of real-life events occurring in Kano, Nigeria.
As the novel opens, Sandy Woodrow, Head of Chancery at the British High Commission in Nairobi, has been eyeing Justin’s wife, Tessa, who is described as being young and free-spirited. Although she comes from a wealthy family, Tessa seems to be constantly seeking ways to rebel against her upbringing, this time by expressing her outrage at the corruption that exists in Kenya’s ruling class, resulting in the vast majority of people living in miserably poor conditions. Tessa is also rumored to be having an affair with a black doctor.
When Tessa gets pregnant, she insists that she have the baby in a local hospital in order to show solidarity for the African women. Her baby is stillborn. Instead, she breastfeeds another woman’s baby who is too malnourished to produce her own milk. Eventually, this mother disappears, and her name is stricken from all hospital records. Suspecting that the drug Dypraxa that the mother had been treated with in the hospital poisoned her, Tessa is determined to get to the truth of the matter.
Tessa and local doctor Arnold Bluhm are convinced that pharmaceutical conglomerate ThreeBees is behind the mother’s death, having given her some kind of experimental treatment. As the two delve deeper into their investigation, Tessa applies pressure on Sir Kenneth K. Curtis, the CEO of ThreeBees. Not long after, she is found dead in a jeep in the backcountry where she was traveling with Bluhm, who is nowhere to be found.
After his wife’s death, Justin seeks to unravel the circumstances of the murder and to pick up his wife’s investigation of ThreeBees. When he examines Tessa’s research, he finds that she and Bluhm had uncovered a trail of drug trials that had been suppressed after patients had died from its use. ThreeBees was still insisting that the drug had been properly trialed and determined to be a success.
Bluhm is being used as a scapegoat for Tessa’s murder and a warrant is put out for his arrest. Meanwhile, Justin is traveling all over Europe and ends up in Saskatchewan, Canada, on his quest to get to the bottom of the Dypraxa conundrum. He meets with Dr. Laura Emrich who tells him that Dypraxa is a dangerous but highly profitable drug, and for this reason, its true effects are being concealed. She tells Justin that the drug is being used in some of the world’s poorest communities in an experimental capacity, essentially using poor Africans as guinea pigs for rich Westerners. As they exit the KVH headquarters, they find that the tires on Justin’s car have been slashed, and they are nearly run over by two prowling vehicles.
It becomes apparent that British officials investigating Tessa’s death are working in cooperation with ThreeBees. Tessa and Bluhm have been killed by hired gunmen at the instruction of ThreeBees because of their ongoing investigation which would have outed the pharmaceutical company as being irresponsible and unethical.
Justin returns to Kenya with a fake passport so as not to expose his identity. He is aware that he must tread carefully, as he feels that his own life is very much at risk. Confronting the higher-ups responsible for continuing to cover up the situation, he gets them to admit that Tessa and Bluhm were on the verge of exposing an International conspiracy and that their investigation revealed entire African villages that had been intimidated into keeping quiet. This confession confirms that ThreeBees, the British High Commission, and the Kenyan government have been working together, all of them aware of the dire consequences of their actions, but continuing to cover it up in the name of profits.
Justin flies north to the place where Bluhm and Tessa began their fated journey. He confronts a man named Brandt who is in charge of receiving and distribution of supplies. Justin recognizes him as one of the men in white coats at the hospital when he visited Tessa in the maternity ward. He knows that this man is also involved in the cover-up mission and the development of Dypraxa.
Finally, Justin hires a fishing boat to take him to the spot where Bluhm and Tessa were murdered. He explores the location where his wife was raped and murdered, and Bluhm was dragged off into the desert to be tortured. Hearing the sound of vehicles approaching, he knows in his heart that it is the same mercenaries who killed the doctor and his wife. He realizes that he is about to die.