IN MIKE LEIGH'S last movie, the underrated Happy-Go-Lucky, the protagonist is a blithe, cheery schoolteacher whose sunny disposition is rattled when her creepy driving instructor makes an unwelcome pass. She's forced to choose between her own inclination to be kind and her need to protect herself, and she decisively chooses the latter. Leigh circles this theme once again in Another Year, a year-long examination of the relationship between a married couple and their needy, unstable friend.

Tom (Jim Broadbent) and Gerri (Ruth Sheen) are middle aged and married, happily puttering about in a bobo interpretation of marital bliss: evenings spent cooking, gardening on weekends, a glass of wine now and then. Gerri works as a counselor, and the receptionist at her hospital is the twittery, blowsy Mary (Lesley Manville), a woman prone to drink too much at dinner parties and fall asleep in Gerri's guest room. For a while, the friendship unfolds harmlessly: Mary a disorganized, well-meaning mess, Gerri gently humoring her nattering friend, to the quiet dismay of her less-sympathetic husband.

But Mary's not as guileless as she initially seems: She's coldly unkind to Tom's old friend Ken (Peter Wight), the one person who actually seems to find her appealing; worse, her interest in Tom and Gerri's grown son is delusional at best. When Gerri senses a threat to the happiness of her family, she doesn't hesitate to close ranks.

Mary's character is a cautionary tale of sorts, a woman clinging unflatteringly to long-gone youth, drinking too much and sobbing about relationships gone wrong, chattering endlessly, ignorant of the irritation and indifference she inspires. Lesley Manville's performance is so effective that the audience cringes along with Tom every time she appears, at once a testament to Manville's performance and to the resonance of Leigh's firm implication that every individual is in charge of their own emotional well being—one can't, like Mary, count on others to provide it.