This is “Oblivion” in a nutshell: The beginning intrigues, and the end excites, but it leaves much to be desired at its core — an adventure left unexplored. “Oblivion” grips you right at the outset and entices you to embark on a promising journey but commits the sin of resting on its laurels for far too long.

It’s 2077. Jack Harper (Tom Cruise, “Mission: Impossible”) tells you that 60 years earlier, Earth was attacked by an alien race. During the course of the subsequent war, humans were forced to use nuclear weapons. Even though the humans won the war, half the planet was destroyed. Jack tells you that he’s now the last man on the planet. His job is maintaining robotic enforces, known as “drones,” which drain the planet of its most essential resources in order to prepare human life to continue elsewhere in the universe. Jack currently lives in a plush watchtower located thousads of feet above the surface of the Earth with his teammate and lover, Victoria (Andrea Riseborough, “Disconnect”). They’re going to go “home” in two weeks.

But Jack isn’t happy.

“Doesn’t seem right,” Jack says. “We won the war … now we have to leave.”

“Oblivion” immediately sucks you into its viewing experience with spectacular establishing shots of a post-apocalyptic world, depicting desolated landscapes and famous monuments such as the Golden Gate Bridge in varying states of demolition. These shots combine with Harper’s eerie narrative to cast a spell over the audience, as each person begins to think and feel like Jack Harper. You know something’s wrong with the situation. You know there’s something else out there. You, too, want answers. You’re as involved as you can possibly be, and you’re willing to be surprised and astounded.

That feeling lasts about 10 minutes.

Ten minutes in, and you’re forced to come to terms with the fact that Jack Harper’s life as the last man on Earth is actually … boring. Sure, viewers are treated to some visually superb shots, and Jack does stumble into interesting experiences with rogue alien survivors (known as “Scavs”). Beyond that, there isn’t any susbstantial plot development that can stand the weight of expectations created at the outset.

You’re waiting for something to happen, but you’re forced to watch on as Jack recounts haunting memories of a time he was never a part of and a woman he’s never seen. Even the introduction of two new characters — an eccentric rebel leader in the form of Malcolm Beech (Morgan Freeman, “The Shawshank Redemption”) and the woman in Jack’s dreams, Julia (Olga Kurylenko, “Hitman”), does nothing to stimulate any meaningful flow of events.

It takes the better part of one hour before things begin to take a turn for the better. By then, you’re most likely frustrated by a screenplay that needlessly drags — exasperated by dialogue that’s shallow at best. It’s almost as if the characters are being made to repeat the same lines in different ways. The pacing is strongly reminiscent of director Joseph Kosinski’s previous venture, “Tron: Legacy” and, at times, serves as an excellent cure for sleep deprivation.

Despite being pinned down by a paper-thin script, the two female leads, Kuyrlenko and Riseborough, manage to deliver memorable performances as Harper’s love interests. The man himself, Tom Cruise, turns in a restrained performance, which is at its best in the film’s quietest moments that see Harper spending time alone with what’s left of the planet.

Due to poor pacing, the majority of the film is left as an exercise in patience and attentiveness, before it attempts to find its way back by exploding onto the scene in an explosive climax. However, having remained in “delta sleep” for most of its running time, you wake up to an ending that leaves you feeling a little dazed and tired.