The best of the big summer movies is also the oddest and - from a marketing standpoint at least - the most perplexing.

If you're from Toronto you're already well aware of Scott Pilgrim vs. the World, director Edgar Wright having been seemingly ubiquitous in the city through the course of the lengthy shoot, determined to use actual locations from the source books as much as possible while also roping in a remarkable percentage of the local music scene. But for everyone else, here's the basic story.

Adapted from a series of graphic novels by Bryan Lee O'Malley -- the sixth and final volume having just been released -- Scott Pilgrim vs. the World is the story of Scott (Michael Cera), a 22-year-old, unemployed slacker coasting through life with a minimum of effort. He shares a bed (in platonic fashion) with his gay roommate rather than buying one himself, plays bass in a middling garage band, is hung up on the end of his only serious relationship from a year earlier, and has just started dating a high school girl to help himself get over that. This sounds predatory when written down but it's not malicious, really, just something that is attractive because it's safe.

Scott's life gets blown into little pieces, however, when he meets Ramona Flowers and is struck by a somewhat one-sided case of love at first sight. Ramona's from New York -- and therefore exotic -- and freshly arrived in Toronto to escape the remnants of a bad relationship of her own. A series of relationships, really. A series of relationships that have formed an evil coalition, The League of Evil Exes, all seven of whom Scott must defeat in physical combat if he is to secure the love of Ramona.

The basic question here is what sort of movie this is. The answer is lots. It's a quirky young adult romantic comedy, fused with martial arts spectacle, with a hefty dose of rock and roll, a dash of Bollywood, and a deep, deep love for classic video games. In an age when movies are built as much by marketing departments as they are by directors, Scott Pilgrim is an anomaly in that it defies easy categorization. There has never really been another movie quite like Scott Pilgrim which makes it a bit of a risk from a marketing perspective. But marketing angles aside what you really need to know is that it's good. Really good. The different parts mesh remarkably well -- the comedy is funny, the action crackles, the cast is uniformly solid and Wright orchestrates the whole thing with aplomb. More than anything else a big summer movie needs to deliver entertainment in every frame and Scott Pilgrim does that in a big, big way.

The success of the film comes from a number of different factors working together. First is the cast. It's a big one and everybody just seems to click. Michael Cera is the key as Pilgrim, of course, but Mary Elizabeth Winstead is just as important as Ramona while Ellen Wong (as Knives) and Kieran Culkin (as gay roomie Wallace) steal pretty much every scene they appear in. On the villain side, Chris Evans and Brandon Routh get to show off unexpected comic chops while Jason Schwartzman is everything you would hope he'd be as the slimy Ultimate Ex.

But the cast would be nothing if not supported by a solid script and firm direction. Without those something as big and complex as this would just splinter and collapse into a great big mess. Luckily this has got both covered. The script was developed with the hands-on involvement of creator Bryan Lee O'Malley, which makes for an adaptation that feels remarkably true to the spirit of the books while Wright steers the ship with a firm hand.

And, finally, there's also what I'll call the Toronto factor. In his quest for authenticity Wright lets Toronto be Toronto, which seems like a perfectly obvious thing to do but you have to know that there was pressure from the studio backers to make this New York or Chicago or some other bis US center. Applauding the choice to keep the setting Canadian isn't just about cheering for the home town -- though it is sweet indeed to see a film that's as obviously in love with the town where I live as this one is -- but it indicates an important dedication to detail. Wherever possible the real locations were used. Where not, they were built in exacting detail. And that attention to detail spills over into all areas of the production. There's a lot of little stuff in this film and the little stuff adds up to a big success because, after all, if you get the little stuff right the big stuff will follow.