What begins with a sniffle and a little bit of wooziness soon has the cast of this South Korean thriller doubled over, spewing forth their phlegm-filled stomachs before hitting the floor like globs of warm mucus – victims of a deadly airborne virus. Director Sung-su Kim doesn’t spend long explaining how the heck this ravenous form of avian flu has come about, concentrating instead on the chaos as the epidemic spirals out of control. And this is where the film hits its snotty stride, exploring the hysteria that, frankly, would engulf us all if we thought our next runny nose would lead to ‘Gangnam Style’ jerking on the floor as we struggled to take our final breath. This is never enough to lift ‘Flu’ from being a predictable romp that’s often just a couple of coughs away from feeling like a spoof. But it will make you think twice before sitting down beside the guy with tissues bunged up his nostrils next time you step on to the tube.