The Constant Gardener (2005) is billed as a romance story and an espionage thriller. It is an unusual combination of character focus, political issues, and scenery, telling a love story against a portrait of third world exploitation.

Tessa Quayle (Rachel Weisz) is a political activist and wife to Justin (Ralph Feinnes), a calm and mild diplomat living a comfortable life. The two are complete opposites in spirit but complement one another. Justin falls prey to Tessa’s natural seduction, and upon Justin’s occupational assignment to Kenya, marries him and follows him on the journey. There, she becomes involved in humanitarian work.

When Tessa is murdered, suspicion is naturally thrown on the shy and reserved Justin. Instead of retreating, he begins investigating her death only to uncover Tessa was quietly exploring an international conspiracy involving multinational profiteering pharmaceutical companies and the British government, which impacts the lives of millions. The progressive story spans multiple countries and continents as Justin works to unearth Tessa’s past, and find the motivation for her brutal murder.

The film is based on a novel by John le Carre and brought to the screen by director Fernando Meirelles. The title refers to Justin’s determination to grow things, literally and figuratively. We see Justin gardening as a hobby, offering gentle but diligent attention to his plants. On a broader thematic level, gardeners never stop digging, and after Tessa’s murder, Justin digs endlessly for the truth. In much of the film, Justin is a portrait of uncertainty. One of the film’s mysteries is the truth of the corruption Tessa was about to discover. The other is how far Justin will go in his investigation. As it turns out, “the gardener” digs too far.

Similarly, one could attribute the metaphor of the title to Tessa, whose constant digging resulted in her murder. She was working to expose the truth of the corporations' nefarious actions, looking to bring information to light. The seed of curiosity was planted in her, and she nurtured it in hopes of blossoming a social uproar and exposure of the facts above the surface. 

Even further, as CinemaBlend observed, “Consider the companies who are continually finding new ways to dispose of bodies and digging and planting, and digging and planting, in an effort to conceal the truth. The idea of a difference in perspective appears.”

Regardless of which character or organization the attribution is given, the title evokes the idea of endless investigation in the pursuit of information. This is the core of the film’s narrative momentum and the idea behind the title.