The protagonist of the film is Justin Quayle, played by the great Ralph Fiennes. He's an easy-going kind of guy, a British diplomat prone to puttering around in his garden. He meets Tessa, a humanitarian, while giving a speech on diplomacy to a bored audience. She stands up and argues her ideals to him, which he takes well. After a discussion, Tessa apologizes, and they go to her house and have a one-night stand. Justin might not think much of it. He may, considering his most intimate moments involve plants.
Whether he expects her to come back is not clear, but return she does, and with a surprising proposition. The proposition is a marriage of convenience, so that she can go to Africa with him. Time passes, and the marriage becomes strained. Justin suspects Tessa of having an affair and is disconcerted by how much time she spends with fellow philanthropist Arnold Bluhm (Hubert Koundé). Tessa is disheartened by Justin's consistent uninvolvement, and a sudden tragedy presses down on them. And then she's gone.
Reeling, Justin focuses on her final project, the unveiling of a conspiracy that she never got to complete. In doing so, he finds himself on dangerous ground but cannot bring himself to return to his plants.
I honestly cannot find much fault with this movie, a well-developed thriller with terrific acting. The cinematography, story, and character are all well-done. I liked the relationship between the two main characters and how it wasn't heavily romanticized or glib like a lot of romantic couples in movies. Unlike the overrated Academy Award Nominee Blue Valentine, the lead characters are likable and engaging. In this movie, Ralph Fiennes proves why he he one of the best of modern thespians. With each facial expression, he conveys a world of emotion. He never over-emotes or "stage-acts" and remains believable throughout the movie.
The only complaints I have are that some of the child actors are not up to par with the script, and the black characters (other than Arnold Bluhm) are not terribly well developed.
Lastly, I think that most people can relate to Justin's involvement with his own personal interests. I think there is more of the constant gardener in us then we would care to admit.