The movie's Sheba is a downy vision of how money and class make swans of certain Englishwomen, which is key to her justification of her sexual indiscretion. The world simply is nothing like the swan pond she expected. Sheba looks longingly at an old photo of herself as a kohl-eyed punk as if to ask, How did I lose what I had? She also plays Siouxsie and the Banshees' 1980 LP Kaleidoscope for Steven, hoping to regain what she lost, not realizing the trap that nostalgia for adolescence sets. Without seeming inordinately spoiled, Sheba clearly feels she deserves a little something more when it presents itself in an unlikely, not to mention illegal, form.

Thus, in the movie Sheba is as articulate, "creative," loving, and hopeful as nature and nurture could make her, so we can understand why ordinary life would not be fulfilling in the way she hoped it would be. At the same time, while Blanchett's Sheba may be more lovely in transgression than we would be, the movie casts Barbara's cold eye on her rationalizations and puts a stop to any romantic daydreaming on our part. The movie presents Sheba more sympathetically than Heller did, and even somewhat indulgently, but the book's fundamental astringency remains.

The script is spectacularly fine, but it wouldn't be nearly as effective without Judi Dench and Cate Blanchett. This makes sense because Marber wrote the script with them in mind, and I say this without being a fan of either actress. Never has a less versatile or more ungiving movie actress than Dench been used as indiscriminately, though it's clear why directors and up-market audiences like her: she marshals and deploys her immense technical resources with military precision. So did the great Edith Evans, but unlike Dench, Evans enjoyed the fancy-dress, the occasion for grand gesture that playacting provided, the mannered dialogue that seemed to call for her archly reverberant delivery (that voice could quaver like a towering fruit-filled Jell-o mold). Dench conveys a sense of gravity, of somewhat humorless duty. She has become the personification of English theatrical skill at a time of morbid self-doubt, Britannia as a corroded but still razor-sharp battleaxe. She may be a great actress, but one who plays both Lady Bracknell and Lady Catherine de Bourg without getting laughs is not my kind of great actress.

All of which makes her perfect for Barbara, and the sophistication and adamantine intelligence that usually keep Dench from melting into her characters is just right for Barbara, helplessly frozen inside herself. It's brilliant casting: that magnificent age-cracked picklepuss emphasizes the precision of the writing because we can see Barbara blasting possibilities with her glance and then retreating even further from what she experiences as a world without possibilities.

Neither has Dench's delivery ever been so pointed — the humorlessness is brilliantly comic here. The imperious way this schoolmarm, this crone uses the term "Madam," for instance, is unforgettable, truly threatening and yet very, very funny. It's a vestige of the most Dostoevskian bits in the book, such as Barbara's disquisition on the ways in which lonely people are such terrible snobs about each other, "afraid that consorting with their own kind will compound their freakishness". Heller, Marber, and now Dench are all capable of insights that make you shudder and laugh at the same time.