By Claudia Puig, USA TODAY

3 1/2 (out of four)

The healing power of love may sound like a cliché, but in Iris, which chronicles the extraordinary bond between writer Iris Murdoch and her husband, John Bayley, one sees the restorative value in the couple's 40-year-long devotion.

But, heartbreakingly, we also see that love — no matter how enduring — cannot cure the afflictions of old age. Based on Bayley's Elegy for Iris, which chronicles novelist/philosopher Murdoch's descent into the dark confusion of Alzheimer's, the movie accurately and painfully conveys the debilitating illness.

As the brilliant and forthright Oxford student, Kate Winslet plays the young Iris with confidence and a lust for life. It's no wonder so many people — particularly men — are drawn to her. The most besotted of all her suitors is awkward fellow student John Bayley (played with endearing gawkiness by Hugh Bonneville), who's a budding writer and, unlike Iris, a virgin.

The film shuffles between the youthful Iris and John and their aged counterparts. As the elderly writers, Judi Dench and Jim Broadbent give incomparably compelling performances. (Note: Oscar is watching.)

Iris is not for the faint of heart. It's unsettling to watch such a brilliant mind lose its moorings. A comment made by the youthful Iris makes her eventual deterioration all the more poignant: "There is only one freedom of any consequence: that of the mind."

As the septuagenarian Iris, Dench so naturally captures the disoriented innocence of those with Alzheimer's that it's almost eerie to watch her transformation. And Broadbent, as her grieving soul mate and overwhelmed caretaker, is a revelation. When Iris gets lost and is returned by a neighbor, Bayley launches a tirade against his barely cognizant wife. His sorrow, exhaustion and anger are so palpable that one's heart aches, for both of them. Despite the sad denouement, it's still the love story of the year.