Director: Christopher Nolan
Cast: Matthew McConaughey, Jessica Chastain, Michael Caine
Certificate: 12A

Note: This contains very mild spoilers. For example, two lines of dialogue. And the description of a planet. If you want to go into this film cold, do not read this review. Or any other review, for that matter.

Imagine, if you will, that you're trapped behind a bookcase. Now imagine that you've been there for an infinite amount of time and you're frantically trying to tell the person on the other site that you need to get some air. Then imagine that a tiny crack suddenly appears between the books, just wide enough for a sliver of paper. So you grab the nearest notepad and start writing. Not just one thing, but everything. Life, family, mortality. It all comes pouring out, an endless scribble of ideas, somehow squeezed into a single ambitious, impossible, wildly uneven message.

That's what Interstellar boils down to.

Matthew McConaughey plays Cooper, an engineer turned farmer in a future where the dust-stormed Earth needs crops, not clever starship pilots. His kids, Murph (Jessica Chastain) and Tom (Casey Affleck), are taught the moon landing was faked and that harvesting corn is the key to humanity's future. Only when they stumble across a NASA base do they learn from Professor Brand (Michael Caine) that the real answer to mankind's survival is in the stars. The plan? Pop into a worm hole and out the other side to find a hospitable planet.

It's a bold leap, driven by a most desperate human urge - but Interstellar struggles to make that jump between the divine and the domestic.

Christopher Nolan has always been a rational storyteller, who believes in manmade miracles rather than mystical fate. After all, he chose Batman as his superhero: a guy with no powers at all. The Prestige, the closest he has come to a film about magic, is more about the deception and guilt of murder than making tiny birds disappear. His work is at its best when communicating emotion through logic or character through structure; Memento's fragmented struggle to move on from something that cannot be pieced together; the haunting grief of Inception's memory permeating the subsconscious.

Interstellar attempts the same thing, stretching the bond between father and daughter across galaxies - hell, even dimensions. When Cooper and his crew - Amelia (Anne Hathaway), Romilly (David Gyasi) and Doyle (Wes Bentley, whose ongoing cinematic comeback remains a delight) - touch down on one water-logged planet, its heightened gravitational force is nothing compared to the emotional blow of realising that one hour on the surface is worth seven years back home; relativity has never seemed more relative.

If that's the movie's biggest achievement, it's one heck of a feat. But it also means it peaks a third into its runtime - because Interstellar reaches out for such greatness, then keeps on reaching. More worlds, more holes, more theoretical physics. Inception's complex structure had a strictly defined limit that sent the film in on itself. Interstellar does the opposite, expanding to galactic proportions.

"We got this far, further than any human in history," declares Brand. "Not far enough!" retorts Cooper. And so they keep venturing into the darkness for 169 minutes, clutching at distant stars.

"Do not go gentle into that good night," Brand is keen on reciting, over and over, to his team; an unsubtle mission statement that feels more syrupy than scientific. It's no surprise that the project began as a Spielberg project based on Kip Thorne's theories, which Nolan later converted.

That wide-eyed streak, so unlike the director's previous work, easily makes Interstellar his most emotional movie to date. It's no coincidence that it also has, in a way, the first happy(ish) ending he has ever written. And the script, co- created with his brother, Jonah, can't quite reconcile that loved-up tone with the rest of film's approach.

And so we have lofty ideas that soar until they reach critical mass, then implode and suck things down to Earth with a bump. It's a strange sensation, which gives rise to awkward ripples in the movie's continuum of earnestness; blips of exposition where the admirable becomes laughably bad.

"Love is the one thing that transcends time and space," argues Annie during one especially earnest discussion. Anne Hathaway's straight face just makes it sound worse. During another decisive turning point, Caine's equally serious professor (only the robots deliver a welcome vein of humour) addresses our departing hero. "By the time you come back," he intones, "I'll have solved the problem of gravity."

Hans Zimmer's overbearing score, determined to conjure up All The Feels, is low on Inception-style BRRRMMMMS because it doesn't need them: the dialogue honks all on its own.

And yet. And yet. There are undeniable moments of wonder here: singularities painted on screen with a fiery brush and multi-coloured arrays of lights that flash across time-bending tunnels. The visuals are jaw-dropping, the kind of thing that makes you marvel at the potential of the universe. You might even start to consider your own mortality. Then Michael Caine pops up to recite poetry and you consider what you're having for dinner.

It wouldn't work at all, if it weren't for our lead couple: McConaughey is magnificent as the intrepid explorer who just wants to get home to his kids, while Chastain delivers real heart as the loyal Murphy, who can't bear to visit her childhood home, which she was convinced was haunted. Their relationship grounds the whole adventure, mostly thanks to a sterling turn from Mackenzie Foy as the young Murph, who gets almost an hour to shine in the first act before her pa takes off. (It's telling that the final third, on the other hand, leaves you gawping at famous actors rather than engaging with characters.)

Those hints of a spiritual world laid early on are, inevitably, dismissed for a a human tale, focusing instead on our race's drive to exist - the key to mindkind's survival, nay for its brilliance. Forget God or aliens, it seems to hint in its most reverent moments; we make ourselves in our children's image.

Of course, it's absurd to even attempt to present these kind of concepts on camera. Even writers who deal with this stuff day in and day out on Doctor Who invented the get-out-of-jail-free adjective "timey-wimey".

As heads spin round and round in the audience, gravity vaguely emerges as central to Interstellar's space-time paradox - but so does love. That balance works until the two collide, Higgs Boson-style, into one heavy-handed climax that carries more mass than the God particle. And after a journey that has taken us to Kubrick and beyond, Interstellar suddenly finds itself back behind that proverbial bookcase, feverishly trying to communicate too much in a ludicrously rudimentary fashion.

"We've always defined ourselves by the ability to overcome the impossible," says Cooper, early on. "And we count these moments. These moments when we dare to aim higher, to break barriers, to reach for the stars, to make the unknown known. We count these moments as our proudest achievements."

It's as much a motto for Nolan's career as humanity - just read the reactions to Interstellar from other directors in this excellent Guardian piece to get a sense of how rare this kind of filmmaking is. It's stunning, ambitious stuff. The result may not go down in history as one of cinema's proudest achivements, but it will be counted as a moment that dared to reach. If Interstellar is ultimately defined by its inability to overcome the impossible, there's no huge shame in that.