Mexican gardener Carlos (Bichir) has lived illegally in Los Angeles since before his 14-year-old son Luis (Julian) was born. When he gets a chance to buy his own truck, and thereby start his own business, he starts to dream of moving to a better neighbourhood to protect Luis from gang influences. But he also worries that if he gets pulled over for any minor offence, he'll be deported and separated from his son. And when his truck is stolen, he knows he has to take action, whatever the cost.

The plot is intensely compelling, pulling us in from the start as we vividly experience the details of Carlos and Luis' happy but precarious life. The sense of danger is intense: a simple accident or bad decision could easily jeopardise them both. And Carlos' more-established sister (Heredia) can only help so much. Director Weitz plays on this uncertainty by quietly shifting the tone and bringing up a menacing musical underscore whenever things threaten to take a turn.

On the other hand, this kind of obvious touch undermines the power of the story, because it distracts from the characters' personal journey by reminding us that we're watching a movie. Yet the script can't seem to help itself: there are constant references to how grim life is on the scary streets of East L.A. One evening as Luis walks home, he passes both a murder crime-scene and a kerbside soup kitchen. He and his best friend (Soto) are also badly tempted by a gang member (Cabral) who twitches and flexes his tattoos in lieu of twirling a moustache.

That said, following Carlos and Luis through this series of events is extremely moving. There are moments of unbearable tension along the way, as well as some warm humour. And while the filmmakers may struggle to wrestle every experience into this one film, they are also telling an important, far-too-common story that highlights the human cost of immigration law.

Lonely and drunk in central London, Will (Menzies) contemplates suicide but is distracted when he sees his local barmaid Eve (O'Reilly) being mugged. He rescues her, but it takes a little while for them to let down their outer shells, relax and start talking. When he offers to walk her home, she invites him to a party, but over the course of the night, thoughts of death are never far from his mind. As morning dawns, they seem to be starting some sort of relationship.

The film has a tender, dark tone, focussing on Will's introspective music and internal turmoil. Fortunately, Menzies and O'Reilly it manages to undercut the depressing atmosphere with offhanded, natural performances that are packed with earthy humour. The camera work is warm and fluid, beautifully capturing the empty night-time streets and the colourful people they meet along the way, including a raucous gang of women on a hen night, for whom Will improvises a very funny song.

As day breaks, the tone stays the same, even with busier streets and glary skies. And if the dialog sometimes gets a bit too oblique and clever, it at least reveals layers of character that are continually subvert our expectations. There's a lot of conflicting emotion in these two people. A scene with Eve's grandmother (Jones) is especially moving, but feels almost like an unrelated short film. Although it does develop resonance in a turn of events that seems just a bit overwrought.

The most powerful sequence is a silent rave that says more without a word than any talky dialog could. And it's fascinating to watch the city wake up around them as they continually look at each other in a new light, while never quite escaping their own personal issues. These kind of inventive touches are what marks the film as something worth looking out for, and it makes us want to keep an eye on what the filmmakers do next.

A homeless man (Hauer), looking for cash to buy a lawnmower to earn a living, finally gets fed up with the violence doled out by ruthless local gangster Drake (Downey), who delights in gruesomely killing anyone who crosses him, including his brother (Wells). Drake's also responsible for the arcade that's turning teens into game addicts with loan-shark debts and a desire for blood. After running afoul of the crooked police chief (Akerman), the hobo is helped by kindly hooker Abby (Dunsworth). Then he gets a shotgun and sets out to clean up the streets.

The out-of-control vigilante plot is full-on, as this hobo "delivers justice one shotgun shell at a time" in garish widescreen B-movie Technicolor. Stir in cartoonish camerawork and editing, camp acting and kitsch dialog, and the film is like an assault on the senses. It also feels like one of those shouty, obnoxious movies that's hilarious if you were in on the joke but doesn't quite translate for an audience. Although if you can get into the groove, it actually has its moments.

Besides Hauer's exhausted tenacity, there isn't a remotely realistic performance here. And the violence is often hyperbolically unspeakable, such as when Drake's sadistic sons Slick and Ivan (Smith and Bateman) attack a school bus with a flamethrower. Meanwhile, Drake deploys a razor-covered baseball bat and two robotic goons. And the cops are viciously hunting the homeless. Of course, it's heading for a contrived Thunderdome-style showdown between the hobo and Drake.

Director Eisener and writer Davies never bother with subtlety, although they stir in some thin emotional moments amid the escalating carnage. Most of this is due to Hauer, who has an undefined backstory that has pushed him to this point. But then, being surrounded by these lowlifes could drive almost anyone to pick up a gun and wash the streets clean. With blood.

Tom (Fisher) leaves his wife and child and quietly takes a train to London, where he starts living on the street. His drop-out idyll is disrupted first by street thugs and then by the smiling, chatty Aidan (Gillen), who lives with his controlling "girlfriend" Linda (Steele). He makes money through odd jobs, including taking his neighbour's (Cohen) cat Treacle into cafes to scare off mice. Tom finds shaking off the clingy Aidan virtually impossible, and eventually starts to soften toward him. Although Linda is another story.

The relationship between Tom and Aidan is reminiscent of Midnight Cowboy, mainly because Gillen seems to be channelling Dustin Hoffman's Ratso with his jittering physicality and child-like persistence. The surprise is that, even though he's seriously annoying, Aidan's relentless optimism makes him likeable. Even when Treacle dies, his grief soon turns to mischievous joy when he adopts Treacle Jr. And Fisher is terrific as a guy reluctantly coming round to see that maybe they can help each other survive.

There isn't much more to the film than this. Thraves slightly over-directs some scenes, pushing small points and straining to be wistful, sad or silly. But there are also very clever touches along the way, both from Thraves and the actors, that more than make up for this. As simple as it is, the story is charming, holding our interest by helping us to care about these two men. There's a sense that this might not end well, and lots of hints about awful things that could happen to them, so we are gripped watching the events unfold.

That said, some of those events are ill-defined (probably deliberately) or contrived. A few things happen that make little sense. For example, where do they find Treacle Jr? It's not like kittens are roaming wild on the South Bank. And some props seem placed for storytelling convenience, rather than internal logic. But these things fade away in the glow of Aidan's hopefulness. And even if the ending is a bit corny, his smile is infectious.