Dame Judi Dench goes nuts with the acting in this high-calorie melodrama, based on a novel by Zoë Heller and adapted by screenwriter Patrick Marber (Closer) and director Richard Eyre (Stage Beauty). Dench plays Barbara Covett, a fearsome history teacher at a British comprehensive school (you know, the type that used to get called a battle-axe) who develops an unhealthy interest in the school's fresh-faced new art teacher, Sheba Hart (Blanchett again, better here than in German). Said interest is countered, or rather inflamed, by Barbara's contempt for Sheba's "trendy politics" and, to Barbara at least, distasteful family: older husband, pouty teen daughter, down syndrome-afflicted son. Said contempt, which is expressed via Barbara's journal, is recited in pungent tones by Dench in voice-over. (Yes, this is another one of those movies wherein the smartest person in the room is also the most emotionally stunted, vindictive, etc.) When Covett (and how about that last name, folks?) discovers Sheba's grievously ill-advised sexual affair with a statutorily young student, she sees a chance to "protect" her new "friend" — in the mad hope, of course, to enfold her and steal her away. When things look not to work out as planned, a betrayal explodes the whole situation. If the resultant wreckage is a little underwhelming, and the film's coda useless and trite, the getting there is pretty absorbing: Marber's dialogue is cutting, Eyre's direction brisk, and the interplay between Dench and Blanchett (who, as a relative naëf, kind of has to play straight woman — no pun intended, given the nature of Covett's pursuit of Hart — to Dame Judi) convincingly roiling.