Roger Michell’s “Enduring Love” is the perfect thinking man’s thriller, a film that is at once an exploration of guilt and obsession and a study in moral and instinctual horror.

The film opens on Joe (Daniel Craig) in the midst of an idyllic picnic in the countryside with his girlfriend Claire (Samantha Morton). Just as Joe is about to ask Claire to marry him, a wayward red balloon bearing a distraught boy sinks to the earth behind him with beautiful surrealism, cutting off Joe’s half-formed proposal and setting off a course of events with disastrous consequences. Joe and several other bystanders rush to pull the balloon to earth, but when a stray gust of air carries the balloon aloft again, all but one of the would-be rescuers drop to earth. Out of a sense of duty or simply panicked indecision, the remaining rescuer continues to cling to balloon as it rises hundreds of feet into the air — until he drops.

Filled with horror and guilt, Joe is unable to put the incident behind him. He talks about the incident ceaselessly, to the discomfort of Claire and his friends. At work, he draws diagrams of the balloon and obsessively tries to remember which man let go of the balloon first. Already on the verge of a breakdown, Joe’s mental health plummets when Jed (Rhys Ifans), one of the other rescuers, calls and begs to meet with him. Jed promises that the one meeting will be their last, and Joe reluctantly agrees to it. But afterward, he keeps calling and begins following Joe to work, to the gym, to restaurants.

Michell relies on neither shrieking violins nor murderers lurking in corners to create moments of nearly tangible tension as the stalking becomes ever more frightening and intrusive. The score is uncannily well-chosen: The tranquility of strains of John Coltrane highlight, rather than detract from, the atmosphere of terror. Whereas a slasher film might startle or terrify an audience, “Enduring Love” engulfs its viewers in a sickening, slow-building brand of fright.

But Michell refuses to let “Enduring Love” rest on its qualities as a horror film. The movie’s greatness lies in its examination of how each man grapples with his share of the responsibility for the death of the balloon’s victim.

Joe, who teaches a college class about the rationality behind all human emotions and values, tries to assuage his guilt by figuring out who let go first and the one man’s motivations for holding on. He obsessively works to determine if all of the men could have brought the balloon down if no one had let go.

The devoutly religious Jed, on the other hand, believes that “everything happens for a reason.” He sees what happened that crucial day as part of God’s plan to bring him and Joe together as lovers.

Craig — recovering nicely from his inauspicious turn as Angelina Jolie’s love interest in “Lara Croft: Tomb Raider” — does a masterful job as Joe. He and Morton give beautifully nuanced performances; they are able to make every complex emotion in the breakdown of their relationship apparent through their facial expressions alone. Ifans succeeds in imbuing Jed with a combination of creepiness and pathos that evokes both revulsion and sympathy. All three performances are intelligent and layered enough to allow the film to succeed as a psychological study as well as a thriller.

Although the script occasionally lapses into banal scenes, such as Joe screaming his frustration into the rain or discovering his own private shrine on Jed’s walls, Michell mostly deals with the subject matter with refreshing novelty. At no point can the viewer rely on the legions of stalker films that have gone before to predict how this taut and ethereal film will end.