Some spoilers follow.

In Oblivion, Tom Cruise's character Jack Harper drives a Bubble Ship, a double-occupancy, hover helicopter of the future that features a long, thin cockpit between two big old orbs. It is close to being an elegant, sci-fi rendering of the Ambiguously Gay Duo's car, and would seem to be the perfect vehicle for Cruise given his own ambiguous reputation. However, there is an even better one: Oblivion itself. The film is a pretty, vacant attempt at thoughtful sci-fi that is too inert to satisfy blockbuster junk cravings, and not deep enough to justify its ponderousness.

The movie opens with an extended scene of Harper hunting down and fixing a bunch of flying drone spheres that patrol what's left of the abandoned Earth in 2077. This lifeless bit of bored busy work is how director Joseph Kosinski (the daft Tron: Legacy) has chosen to introduce us to his world. The excitement barely takes off from there. I sat wondering why I should care about any of this—Harper, his Stepford Laura Linney-like partner Victoria (Andrea Riseborough), the Earth that humans abused for centuries only to evacuate in the wake of an alien attack, the anonymous human stragglers (including Morgan Freeman, in about 10 minutes of screen time) who creep in the Earth's shadows and call on Harper for help. I realized that we're supposed to care because Tom Cruise is steering this thing. Unfortunately, his blank performance makes that impossible.

Granted, his performance is meant to be at least somewhat blank; his memory has been wiped for some reason and he is literally left a blank. In a hilarious parallel to Cruise's actual career, he's a clone, one in a long line of Jacks that do his Wall-E-esque clean-up work in this every-other-movie-esque dystopia. Cruise, too, is part of a long line of Jacks. Here he is Jack Harper. His last movie found him playing the title role of Jack Reacher. In his movie before that, Rock of Ages, he was Stacee Jaxx.

Kosinski is into repetition, too. This is his second movie in a row whose first word announces its setting: "Earth," we hear Harper say, just like Jeff Bridges' character introduced Tron: Legacy by saying, "The Grid." There is a fine line between being helpfully obvious and dreadfully dull. Kosinski veers way too often into the latter lane, asleep at the wheel.

Oblivion is haunted by its superior inspirations like Harper is haunted by phantom clone dreams of an earth he never knew. He lives in a Jetsons-like dome on a pole, he takes direction with the Hal-like Sally (Melissa Leo), he roams the Star Wars-like desert Earth. Cruise looks dead-eyed, as though he's always trying to concentrate in vain, and for someone whose religion discourages medicine, his default mode seems to be pill-zonked. This is the third straight shell of a person he's played: Jack Reacher was described by a fellow character as a "ghost" for being so unknowable and Stacee Jaxx was an intense stare in a codpiece, surrounded by set-piece groupies and ‘80s sonic wallpaper. At least Cruise managed some fire and charm in the former, and at least he got to sing "I Wanna Know What Love Is" into Malin Ackerman's asshole in the latter. Oblivion has no such propulsive energy.

All of these movies court viewers by offering Tom Cruise, and Tom Cruise shows up to be Tom Cruise. In the case of Rock of Ages, the stunt casting was more than half of the joke. In the case of Oblivion, there isn't even a joke. It's a risk-free adventure from a competent actor who's determined to hold onto his eye-candy and content to tread water. Tom Cruise needs to stop letting his celebrity do his work for him or one day he might not have it anymore.