Suffering sheep-phobia after his father's death plunge trying to save a sheep, Henry Oldfield (Nathan Meister) returns to his family's farm to sell out to his older brother Angus (Peter Feeney), who is experimenting with genetic engineering on the sheep, with the help of a small band of scientists. When a couple of animal activists, Experience (Danielle Mason) and Gavin (Kevin McTurk) inadvertently release a mutant lamb into the farm, the ghastly little thing spreads a nasty bug which turns all the sheep into bloodthirsty predators. Henry, Experience and farmhand Tucker (Tammy Davis) find themselves stranded among the herd. As Tucker discovers, one bite from an infected sheep begins a metamorphosis that turns humans into sheep ...

Saturated with blood and memorable monsters, there\'s also plenty of novelty value.

We’ve seen some pretty dodgy killer animals in horror movies over the years, with serious monsters made of worms and grasshoppers, rabbits and shrews, to name but a few in the crazy menagerie.

At first glance, Black Sheep would seem to be taking this notion – harmless fluffy animals – and turning it into a send-up, along the lines of Attack Of The Killer Tomatoes.

But as well as being a funny guy, New Zealand debut writer-director Jonathan King is a horror aficionado - he knows how to make his woolly charges surprisingly scary, especially in the first half of his film.

After a traumatic prank on the same day that his sheep-farming dad died, Henry has grown up into a city slicker, who’s deeply phobic of anything to do with sheep.

With his scheming brother Angus about to unveil his new, genetically engineered sheep for global buyers, Henry has to return to the farm to sign over his half of the business.

But the well-meaning intervention of animal liberationists means one of Angus’ hideous genetic mistakes gets loose – and its bite turns the flock into bloodthirsty zombie versions of their former selves.

With the help of WETA, the special effects outfit behind The Lord of The Rings, Jonathan King has created some memorable monsters.

The zombie sheep are particularly menacing when they’re crowding in like the ghouls from Night Of The Living Dead. It’s this first 40 minutes that’s an expert mix of menace and comic relief.

Henry’s spinelessness makes him an unusual hero, and the activist girl – improbably named Experience - is such an out-there hippie that her flakiness gets some good laughs.

The star, though, is Tammy Davis as the unflappable farm manager Tucker. He’s such a crack-up that the movie suffers when he’s sidelined in the second act.

It’s during this period that Black Sheep wanders a bit off course a bit –a few of the sight gags take us out of the movie, and the crazy mutations aren’t as threatening as the more normal-looking woolly jumpers.

King’s on surer ground as he wraps things up with a pleasingly over-the-top splatter-filled finale.

For genre fans, Black Sheep is packed with nods to horror classics, from The Birds and American Werewolf In London, to Dawn Of The Dead and fellow Kiwi Peter Jackson’s early comic gorefests Bad Taste and Brain Dead.

As a smartly crafted silly movie worth bleating about, this rates 3 ½ stars. Black Sheep is in cinemas August 16.