Leonardo DiCaprio stars as a mind thief who steals secrets from the subconscious in Christopher Nolan's sci-fi action thriller Inception. (Warner Bros. Entertainment)

Remember Memento, writer-director Christopher Nolan’s mind-bending breakthrough thriller from 2000? Well, think of Inception as Memento blown up to blockbuster proportions.

Inception gets stuck in the same ponderous groove as The Dark Knight — and like that film, it’s too long.

Once again we have an ingenious psychological premise and a devious, Byzantine plot. And, once again, we’re left with a film that doesn’t quite measure up to its conceit.

In Nineteen Eighty-Four, George Orwell posited the chilling notion of a Thought Police, but in Nolan’s clever sci-fi vision, we have thought thieves. Leonardo DiCaprio stars as Dom Cobb, a master in this form of subconscious larceny, known as extraction. He and his associates can enter a subject’s mind during sleep and purloin his or her most hidden secrets, using a technology that allows for shared lucid dreaming. (Talk about your collective unconscious.)

Cobb circles the globe, committing his thought crimes for a clientele of ruthless corporate bigwigs. Then, one of the sharks, the Japanese tycoon Saito (Ken Watanabe), offers him a new challenge. Instead of extracting information, he wants Cobb to plant an idea in a rival’s brain. The target is Fischer (Cillian Murphy), the callow son and heir to a dying energy magnate (Pete Postlethwaite). Saito wants Cobb to convince the boy to disperse his father’s empire.

The inception is a complex undertaking that requires inducing a dream within a dream within a dream. To do it, Cobb assembles a crack team that includes his young right-hand man Arthur (Joseph Gordon-Levitt); Eames (Tom Hardy), a snide Brit who specializes in impersonating other people in dreams; and the chemist Yusuf (Dileep Rao), who furnishes the necessary sedatives to induce some serious REM. To build the labyrinth of dreams in Fischer’s mind, Cobb recruits the aptly named Ariadne (Ellen Page), a gifted architecture student recommended by her professor (Michael Caine), Cobb’s father-in-law and mentor.

Cobb’s training workshops with Ariadne turn out to be the most surreal section of the film. Ariadne is a quick study, and before long, she is playfully turning her dream landscape – the boulevards of Paris – into a funhouse of mirrored surfaces and impossible perspectives. For several glorious minutes, Inception becomes the motion picture equivalent of an M.C. Escher lithograph.

As the two enter each other’s dreams, Ariadne discovers Cobb’s own hidden secret, involving his mysterious wife (a suitably dreamy Marion Cotillard) and the reason behind his exile from the U.S. Cobb is hoping to use the inception to end his exile and be reunited with their children, but his mental instability threatens the operation. It’s up to Ariadne to keep him on track when the team finally makes the tricky descent into Fischer’s mental maelstrom.

The early part of the film is engrossing and, despite what the cryptic trailers suggest, the story isn’t difficult to follow if you’re half-awake. Nolan provides his own detailed dream logic. For example, five minutes of waking life equal an hour in a dream (and that’s multiplied for dreams within dreams). He’s also tailored his dream worlds to the action-thriller genre: Cobb’s team has to battle a kind of subconscious security force in Fischer’s mind. And there are so many explosions and implosions that at times it feels like we’re inside the head of a demolitions expert. But Nolan does manage to have a bit of fun from time to time, such as when a team member’s inner urge to urinate unleashes a rainstorm on the dreamscape. He also throws in plenty of references for movie geeks. You’ll spot allusions to The Matrix, 2001: A Space Odyssey, Fantastic Voyage and even, if I’m not mistaken, Jean Cocteau’s The Blood of a Poet.

Ariadne (Ellen Page) gets a peek into Cobb's troubled dreams in Inception. (Warner Bros. Entertainment)

Finally, though, Inception starts reminding us again of Nolan’s shortcomings as a filmmaker. In the years since Memento’s release, the British director has gone mainstream and most famously helmed the Batman reboots, Batman Begins and The Dark Knight. He now commands nine-figure budgets and can do awesome things with state-of-the-art special effects and international locations – Inception takes us from the narrow alleys of Tangiers to Alberta’s snow-shrouded Fortress Mountain. But there doesn’t seem to have been a comparable increase in his artistic range.

Inception gets stuck in the same ponderous groove as The Dark Knight — and like that film, it’s too long. The way Nolan juggles the different dream time frames, dexterously edited by Lee Smith, is at first audacious, but then grows tiresome. Finally, his imagination fails him. Planting a movie, even a genre one, in the field of dreams offers rich possibilities that he fails to cultivate. At one point, Eames tells Arthur, “You mustn’t be afraid to dream a little bigger, darling,” and you wonder why Nolan didn’t follow that advice himself.

He also doesn’t make full use of his excellent cast. DiCaprio, once again playing a man tormented by his past (see Shutter Island), gives a commanding performance. His co-stars, however, get little chance to develop their roles. There’s some mild antagonism between Eames and Arthur, but it leads nowhere. Page’s dream-weaving Ariadne becomes Cobb’s confidante, but we learn nothing about her and there’s no emotional connection between them. Only Murphy’s Fischer, and Tom Berenger as his avuncular adviser, are fleshed-out characters, and then it’s because the plot necessitates it.

Before I stop carping, I also have to say that, despite Guy Dyas’s elaborate production design and Paul J. Franklin’s dazzling visual effects, Inception never really evokes the sensation of dreaming. Other films with more modest budgets have been able to do it – Richard Linklater’s Waking Life springs to mind, not to mention most of the works of Luis Bunuel. Nolan’s ambitious dream architecture lacks a true sense of the absurd.

But I may be demanding too much from what is, after all, just a summer blockbuster. Next to dim-bulb movies like The A-Team and Knight and Day, Inception looks like a work of incandescent genius.

Inception opens Friday, July 16.

Martin Morrow writes about the arts for CBC News.