However, among the grass skirts and widescreen vistas is a thrilling horror plot, namely a killer couple prowling the islands for other conjugal victims. Cydney and Cliff are on full alert, as each new development on their vacation provides yet another mysterious couple to feed the flames of paranoia. Before long, the plot unveils a glut of potential candidates for who the killers are, including the grungey, dysfunctional Kale (Chris Hemsworth) and Cleo (Marley Shelton), and the earthy, charismatic Nick (Timothy Olyphant) and Gina (Kiele Sanchez). It’s an obvious, almost bland set-up, with a twist that, while admittedly unconventional, can be spotted a mile off. However, evidence indicates that Twohy and co were in on it, and sought to make the proceedings charmingly fun, if not the least bit groundbreaking. The cast, crystallised into the central ensemble of Zahn, Jovovich, Sanchez and Olyphant, have a casual, ever-so-slightly campy chemistry that stays on the right side of enthusiasm, and never feels calculated. The film manages to be laid-back, economical – a light, 98 minute snack – yet still indulges in long scenes of inter-character banter, with Olyphant’s long-form, barrel-chested monologues about his adventures as an ‘American Jedi’  (including the discovery of a Middle Eastern dictator’s Silver Age comic collection) providing intermittent comedy. The final-third shift into a slasher flick is clumsy – all manipulative shocks and convoluted tension – but some flashy, darkly humorous gore, and a flat-out bonkers flashback sequence, filmed in stark Redcam monochrome, keep the entertainment factor going until a suitably convoluted, corny conclusion. The end result is like a spunky mix of Hostel and Scream, with a dash of Natural Born Killers, starring disarmingly beautiful (and bronzed) actors, set in a gorgeous tropical climes and shot like a travel advert (the irony is, however, that the film was shot in Puerto Rico for the tax breaks, and the Hawaiian backgrounds are all VFX trickery).