Inception (PG-13) ★★★½

Christopher Nolan has always been something of a mad-scientist filmmaker, mixing together seemingly incongruous elements from different genres to create dazzling concoctions like Memento, The Prestige, Batman Begins, and The Dark Knight. He continues his genre-splicing tradition with his ambitious new opus Inception, an engrossing head-trip that might be labeled an existential sci-fi heist flick. But that would be oversimplifying things.

Leonardo DiCaprio stars as Dom Cobb, a professional thief who specializes in swiping not cars or diamonds or paintings but intellectual property. What sets Dom apart from the typical Chinese hacker, and what makes his services so appealing to his powerful corporate clients, is his expertise in "extraction," a process whereby he utilizes a cutting-edge process known as "shared dreaming" to enter the mind of the mark while he or she is sleeping and steals information directly from their subconscious. (The nuts and bolts of "shared dreaming" technology aren't ever explained, and only obliquely referred to as an innovation of the U.S. military.)

Dom is a reluctant criminal, a former academic forced underground after authorities unfairly pegged him for the murder of his wife, Mal (Marion Cotillard). Weary of his itinerant fugitive lifestyle and longing to be reunited Stateside with his two young children, he agrees to take on a dangerous new assignment — his One Last Job, in heist film parlance — from an energy mogul named Saito (Ken Watanabe), who pledges to clear his name (in the movie world, fugitive suspects can be exonerated with a simple phone call from a CEO) if he can convince the heir of a rival energy conglomerate, Robert Fischer (Cillian Murphy), to dissolve his ailing father's empire after the old man passes on.

The danger of the new job lies in a key detail that distinguishes it from previous ones: Instead of extracting an idea from Fischer's brain, Dom will need to implant one — a significantly riskier and more complicated process dubbed ... wait for it ... "inception." To pull it off, Dom and his right-hand man, Arthur (Joseph Gordon-Levitt), assemble a crew consisting of the best and brightest in the shared dreaming field.

As you might have gathered, Inception's waking life/dreaming life construct is a complicated one, and fraught with all sorts of weighty existential implications. To make it all work, Nolan must devote the vast majority of the film's dialogue to simply laying out the various rules and caveats: dreamers are given a cocktail of sedatives to maximize REM sleep; when they die in a dream, they awake in real life; if they don't die, they can be awakened with a "kick," which ranges in intensity from a classical music melody to a punch in the face; each dreamer carries a "totem," a sort of personalized cogito ergo sum device to help them distinguish between reality and dream in times of doubt; and so on.

One of Nolan's more admirable traits is that his films, no matter how fantastical they might get, are always anchored in a certain logic, with a premium placed on scientific accuracy. If this were an Ocean's movie, Soderbergh would have glossed over the above in a dizzyingly hip montage set to a swingin' Elvis dance remix. But for Nolan, the details are essential. Which might make great fodder for fanboy forums, but it leaves precious little room for other important narrative tasks, such as developing the supporting characters, who, unlike Inception's subject matter, are uncomplicated and thinly drawn. (In perhaps a cheeky nod to this fact, Ellen Page's character, the crew's rookie member, chooses a chess pawn as her totem.)

Inception's avalanche of information (at one point juxtaposed with an actual avalanche, for irony's sake) becomes so intense you almost expect the film to simply seize up, a giant spinning hourglass appearing on the frozen screen, as Nolan's relentless download finally overwhelms our ability to process it all in real-time. Tasked with pondering both the dramatic and philosophical ramifications of every action, our grasp of the plot grows ever tenuous, making it increasingly difficult to distinguish between events occurring in the past or present, between characters real and imagined, between heroes and villains.

If there are any villains. Saito and Fischer, the scheming corporate titans whose rivalry catalyzes Inception's storyline, both gradually emerge as sympathetic characters. A simulacrum of Dom's deceased wife pops up at inconvenient moments to sabotage his efforts, as do a phalanx of anonymous goons spawned by one character's subconscious, but neither feel like genuine antagonists. As such, the film's blistering climax loses much of its impact. The explosions and gun battles and zero-gravity fist-fights are all amazing, truly, but it's unclear what the point is to all of them. Inception, though always riveting, isn't always comprehensible.

Hollywood.com rated this film 3 1/2 stars.