The world’s worst skin condition returns, trading in the cabin in the woods and the high school prom for an idyllic Caribbean island, where a quartet of pretty young things can be found celebrating one of their number’s impending nuptials. Idyllic, that is, until super-infectious Sean Astin (Samwise Gamgee himself, only wearing a beard) sets loose a particularly nasty strain of flesh-eating virus, well and truly ruining the holiday for everyone.

Drama and film students will be familiar with the dramatic principle behind ‘Chekhov’s gun’, which decrees that, if you’re going to put a gun on the stage in the first act, you’d better have someone use it by the second. Substitute that gun for a big black dildo, and you’ll find that Patient Zero follows Chekhov’s rule pretty rigidly. Sure enough, the enormous rubber lovelength introduced in the film’s first act is used to particularly grisly effect during its (no pun intended) climax. And that, ladies and gentlemen, is possibly the only time you’re going to see a reference to Anton Chekhov in relation to Cabin Fever 3… or giant rubber recreational devices, for that matter.

Where Cabin Fever 2 was a low point in director Ti West’s so far illustrious career, Kaare Andrews’s Patient Zero is something of a return to form for the franchise. It’s a slicker, more professional looking movie, well-directed and acted throughout. Similar in tone, style and pace to Eli Roth’s Cabin Fever, it’s a better companion piece to the original film, and far more watchable to boot. Even better, it doesn’t have Giuseppe Andrews in it, whose dodgy performance should have been left as one brief scene in the first film, rather than extending into (and spoiling) its sequel. There’s a distinct lack of Justin and Doctor Mambo, though, which is disappointing.

In Sean Astin, Patient Zero has a respectable if slightly bizarre star name. He’s not enough to draw an audience as such (save for fans of the Mr. Frodo/Samwise Gamgee bromance) but he does lend this straight to DVD sequel a sense of legitimacy sorely lacking in most budget follow-ups to respected features. While it tells more or less the same story as Cabin Fever, there are enough grisly death sequences and nastier moments of body horror to justify its existence. A lot of it is predictably done (the guy going down on his infected girlfriend was never going to get a happy ending) but much of the entertainment in these films is in seeing the inevitable unfold. Case in point: the aforementioned big black dildo. We all knew it was coming (again, no pun intended) but that doesn’t make it any less welcome. Gory and practical, the effects do a fine job of portraying the virus at its most vicious, even if it does steer a little too close into well-trodden zombie territory for comfort. Furthermore, while the island setting is nice at first, it all too soon descends into pitch-black government basements and dingy corridors.

Patient Zero is a fine addition to a franchise which has been in remission for too long. Quick, cruel and enjoyably crass, its sense of enthusiasm is charmingly infectious.