It's the end of April. Sergeant Howie (Edward Woodward) arrives by seaplane to the remote British island of Summerisle. The police had received a letter and photo of missing 14-year-old girl, Rowan Morrison. At first, no one in the village recognizes the photo. The letter about the missing girl was anonymous.
Sergeant Howie goes to the Morrison family, the mom runs a candy store. She has one daughter but doesn't have another, no missing Rowan. Everyone isn't being totally obtuse, just cheerfully unhelpful.
Sergeant Howie spends the night at the Green Man Inn. Everyone is there, it's the local pub, singing and kissing. The innkeeper's daughter has a beautiful daughter Willow (Britt Ekland). Their songs are about sex, semi-subtly. Officer Howie goes outside and everyone is having sex on the lawn. He goes back inside to see a kilted man offering his teen son to Willow. They play a song about coupling. Sergeant Howie is Christian and wracked with guilt about these fornicators.
In the morning, all the school boys are practicing the dance around a maypole with a singer, it's almost a musical. The girls are inside with their teacher, Ms. Rose (Diane Cilento). Sergeant Howie is still looking for Rowan. Ms. Rose says she's not there but he grabs her roster and Rowan's name is listed as a student. Ms. Rose and Sergeant Howie talk outside, and she basically says Rowan is dead. Sergeant Howie goes to the records office, there is no death certificate for Rowan. All the townsfolk keep questioning Sergeant Howie's authority to be there at all.
Sergeant Howie visits Lord Summerisle (Christopher Lee), who explains that they all worship the Earth. Sergeant Howie asks to dig up the coffin, he doesn't appear to get permission so he does it at night. Inside there is a giant hare instead of a human body.
Ms. Rose is at Lord Summerisle's house, they're singing together. Sergeant Howie throws the hare at them. They say this is Rowan, she changed.
At the Inn, Willow sings a seduction song and bangs naked at the wall trying to get police officer to come over to her room. Sergeant Howie barely manages to stay away, as a good Christian he is engaged but a virgin. He tries to leave May 1st but his plane won't start. He looks up pagan rituals about May day.
Back at the Inn, Sergeant Howie goes to rest since he can't leave yet. Willow and the innkeeper say they'll use a special thing to keep him asleep. Instead Sergeant Howie wakes up, and sees a strange burning hand/candle. Sergeant Howie knocks out the innkeeper and puts on his fool costume.
Previously, Sergeant Howie had searched all over and found that last year's harvest was bad. He's convinced they're going to sacrifice Rowan for a better harvest. The town marches and does their May day ceremony, they are led to Rowan, she's alive and fine. Sergeant Howie unties her and runs away with her but it was all part of the plan to get the police officer, a Christian virgin to come to the island of his own free will so they can sacrifice him to have a better crop yield. Sergeant Howie tries to get them to stop, but they put him in the wicker man, where there are also a bunch of animals in cages and they're all burned at sunset.
Great crazy folk horror vibes. I already knew the basic plot so the town trick wasn't a surprise, but it was still fun. There's so much music it could be a musical, there is a folk theme song called Corn Rigs. Christopher Lee is so young in this one!
