Priscilla has never had an orgasm. It is beginning to take its toll on her marriage, and her despairing husband Jack now considers their relationship as nothing more than "ten years of failed f**king." After a decade of energetic and time-consuming attempts, Jack has lost his sense of pride, and wanders around the high school where he works, looking dishevelled and distracted. Although he is a young, good looking man, his bearded, tweedy appearance tells the world he feels unloved, and doesn't see the point in loving himself anymore.

Priscilla meanwhile is wound up way too tight. She arrives at work looking pristine and immaculate, as if she has just stepped out of a zip-locked plastic bag, and uses a water spray to seal envelopes, rather than licking the seal. She is "an unmeltable ice cream" and decides to seek advice from a sex therapist about her "sexual dysfunction".

Priscilla's belated journey of self-discovery leads her to a sex shop where she buys a vibrator. Her initial cautious dabbling turns into a full-blown addiction that speeds up the demise of her marriage, and both partners seek comfort and explore new territories with other, very unlikely partners.

There are several enjoyable cameos - including Mischa's Barton's sexually precocious biology student, and Liza Minnelli's sex guru, who teaches classes about the healing power of masturbation, and flounces about in a sequinned jacket, telling her pupils to "value your vulva".

Danny De Vito is also surprisingly charismatic as the cheesy pool salesman who turns out to be more soulful and romantic than anyone would have guessed. While it is a relief to watch Priscilla transform from frigid perfectionist into a sweet, vulnerable girl, the journey is not quite as satisfying for the audience as it could be.

Too much reliance on slapstick comedy - and a ridiculous scene with a vibrating pager down Priscilla's pants - moves this away from an interesting, modern sex comedy, into the silly, fluffy realms of predictable rom com.