It seems like the perfect job for a governess: she has been appointed to look after two apparently angelic children in a beautiful country house. But, quite naturally, she is apprehensive. "Very soon I shall know what's in store for me," she sings in Benjamin Britten's opera The Turn of the Screw. Beneath the words, Britten adds an unnerving and insistent beat on the drums, suggesting that problems may lie ahead.

And so it turns out. Children Flora and Miles start playing up, and Mrs Grose, the housekeeper, lets slip that Miss Jessel, the former governess, and Peter Quint, the master's valet, both died in mysterious circumstances. She further alleges that Quint "made free with Master Miles and Flora". You are bound to wonder if a sexual agenda is included among the dark secrets lurking in the past, and in this Oxford Opera Company production, director Sara Jonsson seems to confirm that suspicion through the use of body language - the ghosts of both Quint and Jessel appear, and certainly don't give the impression of being harmless apparitions. On one unsettling occasion, Quint's ghost gives out ambivalent signals as he creeps rather too close to the children.

Britten adds spare but descriptive orchestral colouring to this tale of good versus evil. The music is constructed to a rigid tonal sequence, but conductor James Ross never allows this fact to impinge on the vitality of the performance. Using Britten's full score for 13 players means that the singers sometimes fail to project their words above the orchestral sound - North Wall has no pit. But good acting and body language skills make up for the shortcomings in vocal projection, with characterful performances from Heather Uren and Toby Pleming as the children, Sara Jonsson providing a regal yet humane governess, and Fiona Dobie excellent as the steadfast housekeeper. Meanwhile, you feel a real chill every time Katherine Cooper and Adam Tunnicliffe appear as the ghosts.

There are further performances in Hertford College Chapel tonight, and on February 20 and 22. Tickets: 01865 305305 or www.ticketsoxford.com