An assortment of Korea’s most unsavoury criminals is being extradited from the Philippines on board a rusted hulk of a container ship. An elite squad of police is guarding them – inadequately, it turns out. Carnage ensues.

But if you are expecting a Korean-language Con Air scenario, with added water and considerably more knife violence, think again. The tittering psychopath with the tattooed buttocks and the entourage of heavily-armed flunkeys is by no means the most dangerous thing on the boat – a boat that is bilge-deep in blood and assorted viscera within the first 20 minutes.

The violence is exuberantly over the top – somebody gets their face punched clean off, another is beaten to death with their own severed arm – but the inventively relentless action is rather let down by a screenplay that is leakier than a minor supporting character after one of the many stab rampages.

Approach with a strong stomach, and don’t bother trying to keep a tally of the body count.