The creative siblings behind The Matrix trilogy, Lana and Andy Wachowski, team up with German filmmaker Tom Tykwer (Run Lola Run) for a bold cinematic adaptation of David Mitchell’s equally ambitious novel, Cloud Atlas, that proves sprawling, provocative, and epic in scope, while also likely to alienate large portions of its target audience.

As is the case in Mitchell’s novel, the film version of Cloud Atlas follows six narrative threads, each based in a different century, following an assortment of characters and told in a variety of styles, but which all share common themes, messages and at times overt references to one another. Structurally, however, the film and novel are very different. Mitchell begins his novel with the oldest story, or that set longest ago, and tells it chronologically, stopping just before its climax to move on to the next. He repeats this until he reaches the sixth story, set in a primitive post-apocalyptic future. This segment is told in its entirety, before ushering in the denouement of the penultimate story, which in turn introduces the finale of its predecessor, and so forth, until the book finally ends back at the first tale, thus coming full circle.

The screenplay for Cloud Atlas, also adapted by its three directors, cuts back and forth between all six of its stories throughout its duration, and actually chooses to bookend its narrative with the final, futuristic tale that appears at the centre of Mitchell’s novel. Despite this, the main connection between each story remains the same, a character is in some way reading or learning about the events that took place in the story that preceded it. High praise must be given therefore to the film’s editor, Alexander Berner, for intertwining these stories so immaculately, so that not once during the film’s 172-minute running time is the audience lost or in doubt as to which story they are currently following.

In true cinematic fashion, the filmmakers are able to weave the segments into each other in another way, a method that was unavailable to David Mitchell when he was writing his novel. Tykwer and the Wachowskis have assembled a fine ensemble cast of 13 international A-list performers, whom they use to tell all of the half-dozen different tales. While the cast includes Caucasians, Asians and African-Americans of both male and female genders, the directors make very deliberate decisions not to let such frivolous, ineffectual differences come between them and the story they wish to tell. Unsurprisingly this decision proves to facilitate one of the overriding messages of Cloud Atlas.

To briefly summarise the six stories and how they connect to one another – without spoiling anything:

1. In 1849, a young American lawyer named Adam Ewing (Jim Sturgess) has come to the South Pacific to broker a deal on behalf of his father-in-law (Hugo Weaving). After falling ill he sets sail for home, accompanied by the attentive Dr. Goose (Tom Hanks), only to discover a Moriori slave (David Gyasi) has stowed away on the ship.

2. Robert Frobisher (Ben Whishaw), a young bisexual musician, is forced to flee Cambridge in 1936, and heads to Edinburgh, where he becomes amanuensis to a famous yet reclusive composer (Jim Broadbent). While working on “The Cloud Atlas Sextet”, he reads a book entitled The Pacific Journal of Adam Ewing, and writes of his experiences to his lover back home, Rufus Sixsmith (James D’Arcy).

3. Now much older, Sixsmith works at a controversial nuclear power plant in San Francisco, circa 1973, and encounters Luisa Rey (Halle Berry), an investigative journalist looking into the plant’s practices. Sixsmith agrees to help with her investigations, which proves dangerous for both of them.

4. In present day England, veteran publisher Timothy Cavendish (Broadbent) is struggling to find a hit, instead stuck with trying to sell manuscripts like “Half-Lives: The First Luisa Rey Mystery”. When the memoir of a notorious criminal (Tom Hanks) proves a hit, he finds himself suddenly on the run from his client’s gangster pals, and is tricked into checking into a retirement home by his brother (Hugh Grant). Now Timothy must band together with the other geriatric inmates and stage an escape!

5. In New Seoul, 2144, an android waitress named Sonmi-451 (Bae Doo-na) is being interrogated before her execution. Her story tells of her daring escape from servitude, her subsequent enlightenment and desire to teach the society above that it is also trapped and in need of leadership and freedom.

6. On the remote islands of Hawaii, “106 winters after The Fall”, a primitive tribesman (Hanks) lives a simple life, plagued by the threat of rival tribes and his own inner turmoil. When a mysterious woman (Berry) arrives from across the sea, he is persuaded to guide her through dangerous terrain and up a mountain, for reasons she chooses to keep secret.

These are just the bare bones of the stories, which are brimming with subtle and more overt references to each other, as well as many recurring appearances from the major cast members. Each story is told within the trappings of a particular genre, be it epic period adventure, 70s conspiracy thriller, lighthearted comedy or hi-tech sci-fi thriller, and while tonally this is a challenge for the filmmakers, they execute it masterfully, finding a pitch-perfect harmony between the different action beats, romance and drama of the six stories.

And so we return to the casting decisions, which is likely to provoke most of the discussion surrounding the film. There are numerous occasions in the film where actors portray characters of differing ethnicity to their own. Halle Berry plays a Maori tribeswoman, an Indian and a Jew as well as black characters. Similarly, Chinese actress Zhou Xun plays a Hawaiian woman, while South Korean Bae Doo-na appears as Caucasian and Mexican characters, in addition to a Korean-esque robot. Most troubling to some local viewers might be the sight of white actors, including Jim Sturgess and Hugh Grant, made up to look Korean.

Others get the opportunity to play characters of opposing gender and the results, unsurprisingly perhaps, are often met with a humourous or slightly perplexed response. I am reluctant to spoil some of these casting decisions as they are meant to surprise and entertain the audience, judging from how they are revealed onscreen. I only hope that these decisions do not spark any kind of discussion about the political correctness of having people impersonate other ethnicities.

Nobody is poking fun at race here, or in any way disrespecting it. The film is attempting to make a number of bold statements about the universal oneness of humanity, how we are all the same on the inside, regardless of how we look on the outside. Also, the film has an overriding theme of reincarnation and immortality, how our souls live on through the ages, again, inhabiting different bodies and taking on different appearances as they go. It must be said that these decisions don’t always work, and on occasion pull the viewer out of the movie, but that is simply the shock of seeing a familiar face suddenly rendered unfamiliar, rather than any kind of moral outrage. Also, it would be wrong not to mention that for co-director Lana Wachowski, the themes of gender, identity and self must have struck a particularly personal note.

Beyond all that, Cloud Atlas is just damn fine filmmaking and tells a story – or a number of stories, all of which become, yes, one story – that is by turns romantic, exciting, funny, tragic, thrilling and in the end pretty powerful. These directors know their genres and each segment, much like what Leos Carax accomplished in Holy Motors, feels true to its specific roots, while never betraying the grand over-arching narrative. Some segments are obviously more effective than others – 1,3 and 5 were my personal favourites – but they all work in their own way.

The same can be said for the performances, with Tom Hanks proving particularly impressive. Apparently something of a hero behind the scenes, whose commitment to the project was sometimes the only thing keeping it afloat, Cloud Atlas not only marks the first time Hanks has ever branched into science-fiction, but you will be hard-pressed to find another instance of him spewing such foul-mouthed profanity as he does here. Hanks is clearly having a ball and it proves incredibly infectious.

The risk with such a large supporting cast is that the collective is often forced to carry one or two members for the sake of their star power or international recognition. However, that really isn’t the case here. Sure, there are a couple of wavering accents along the way, but the performances themselves are rock solid, and if you’re not already in love with Bae Doo-na (I am) then you most certainly will be by the time Cloud Atlas ends.

The film is by no means perfect, but the kinks and imperfections along the way quickly disappear in the shadow of the film’s incredible achievement simply in existing. It is such an audacious undertaking that if Tykwer and the Wachowskis had only achieved half of what they accomplish here, we would still be praising the film’s bountiful merits. It is a challenge to watch – it’s long, it is uneven, it is daring in its storytelling and casting – and those looking simply to switch off and be mindlessly entertained will quickly be overwhelmed by what Cloud Atlas presents to them. Viewers with a more adventurous appetite, however, are in for a beautiful, unique, and quite fantastic ride.