Murphy and Newton play extremely well alongside each other. Jamie Bell also delivers a solid performance, showing real versatility, changing from innocent stranger to violent thug in seconds. Known primarily for his role as Billy Elliot, this is his most memorable role since. Of course, he's in next month’s The Adventures of Tintin as well, or at least his voice is, so maybe this is a new start - from this performance alone, I'd definitely like to see more.
However, with a cast of just three, proceedings come close to being unenjoyable at times when the third character is such an unlikable psychopath. The trio verge on the boring but the film breaks away from this restricted focus at just the right time and it is at this point that it gets interesting. Notably, it is only in the last half an hour that the you are unable to take your eyes away from the screen, and you do find yourself screaming “JUST BLOODY SHOOT HIM!” a number of times - the final few twists really pick the film up.
Reviews have focussed on the lack of gore in this film. But why does it need gore? That’s what keeps the suspense high throughout the film. We don’t know if the virus is really out there or if it has been made up, so a clean and healthy setting makes us believe that everything is safe, whatever the outcome.