Misunderstood even by its own studio at the time of its release, director Robin Hardy’s debut film, a tale about a prim Scottish police sergeant investigating a missing-child case on a private island, uses a fiendish, economical screenplay by Anthony Shaffer to mock everything in its path, even itself.

Sergeant Howie (Edward Woodward) is stonewalled by the locals from the second a police helicopter deposits him on remote Summerisle, a Scottish burg known for its capacity to grow produce. It initially seems like this will be a straightforward case for the experienced lawman, but it’s actually something altogether kinkier, thanks to the prurient islanders.

Howie, a devout Christian, is appalled by the pagan sexual rituals performed openly and wantonly by the isle’s batshit inhabitants, who like to pray, dance and sing naked. Even the chaste Howie has to look twice when the tavern owner’s bawdy daughter Willow (Britt Ekland) displays her charms. And Lord Summerisle (Christopher Lee), the village’s leader, may be the biggest wackjob of them all. Trying  hard to focus on his work as the town’s licentious Mayday festival approaches, Howie interrogates one lewd, lying local after another as he zeroes in on the missing girl, who may have been murdered in some sort of sick ritual sacrifice.

What’s amazing about Wicker Man is that despite lazily being labeled a horror film, it’s really a breezy and funny whodunit until its famous conclusion, almost working as a comedy of manners, as joyous as it is sinister. It’s like an elaborate practical joke, albeit one being played by bloodthirsty pagans. The amusement emanates not only from Howie’s stunned reactions to the gleeful heathenism but from the good Christian looking down on the islanders, conveniently forgetting that his own religion is based on a brutal sacrifice. “You’ll simply never understand the nature of sacrifice,” Howie is told at one point, but what he can’t understand he may have no choice but to accept.•