Ella (23) a DPhil student at Oxford is awarded a bursary to continue her studies. Her tutor, Andrew (39), a specialist in present-day pagan rituals and object of her youthful desires, encourages her to travel and experience rather than pore over dusty tomes in the college library. He dismisses the festivals of Up Helly Aa and Jack Frost vs the Green Man as suitable avenues of research. The compromise they reach is May Day in Padstow for the feast of Beltane and the quest of the Obby Oss.
Unimpressed by the Obby Oss, Ella is told of an unusual Punch and Judy show. Intrigued, she watches the macabre show of Punch and the crows.
Back at Oxford the discovery of a cryptic sign leads her to the Cornish island of Collane and a little known Lammas Day celebration, the Crow Fair. Determined to investigate, she meets with unexpected opposition from Andrew who reveals that his birth mother, Hazel, lives on the island and if such an event existed she would surely have told him. Undeterred, Ella persuades Andrew to accompany her to Collane.
Hazel must obtain permission for the visit from Lord Collane. At their meeting she reveals that Andrew is his illegitimate son whom she gave birth to on the mainland and never spoke of, fearful that the Crow Fair tradition of sacrifice would claim her only child. With the realisation that he has an heir, Lord Collane insists that Andrew and Ella be his guests at the Crow Fair.
Upon arrival Ella is invited to meet with Lord Collane where he reveals that he is the mystery benefactor of the bursary and proceeds to tell her about the Crow Fair, insisting that she take the part of the scarecrow in the day’s proceedings.
Hazel is concerned when Andrew is ordered to join Lord Collane on the day of the Crow Fair. The procession begins with the blackbird children surrounding the scarecrow. Ella playfully chases the children as they head towards the cornfield, but the events take a sinister turn as the blackbird children are frightened away by the appearance of 13 huge human crows who capture and restrain Ella, as Andrew joins his father in the cornfield to witness the ultimate sacrifice of Ella.