Maya Angelou compares jealousy in a relationship to salt in food. "A little can enhance the flavor, but too much can spoil the pleasure and, under certain circumstances, can be life-threatening." This multi-leveled movie contains two narratives; one is about a contemporary marriage unraveling, and the other explores a double murder in 1873. Alice Arlen and Christopher Kyle have adapted Anita Shreve's best-selling novel for the screen with its portraits of two women from different eras seething with feelings of toxic jealousy. Kathryn Bigelow (K-19: The Widowmaker) directs this psychological thriller with a keen appreciation for the emotions that lie behind disappointment, betrayal, and rage.

Jean (Catherine McCormack) is a photographer who is working on a piece about a 100-year-old murder that took place on the Isles of Shoals. Her husband Thomas (Sean Penn), a Pulitzer prize-winning poet, convinces his brother Rich (Josh Lucas) to take them to the place on his boat. Both are stunned to discover that he has invited his lover Adaline (Elizabeth Hurley) to join the excursion. She turns out to be a huge fan of Thomas and quotes some of his poems from memory. Jean is immediately jealous of this sexy woman who dons a bikini and begins flirting with her husband, who obviously enjoys the attention.

While her own emotions begin to swirl around inside her, Jean is drawn into the mysterious murder of two Norwegian women. At a trial, Maren Hontvedt (Sarah Polley) claims to have witnessed the killings by a former boarder — Louis Wagner (Ciaran Hinds) — in the home she shares with her husband (Ulrich Thomsen). This fisherman was hanged to death for the murders. But while looking for photographs in a mainland library, Jean finds a diary written by Maren and learns the complicated truth about what really happened that fateful day in 1873. It turns out that Maren is a woman roiling with jealousy over the pretty new wife (Vinessa Shaw) of her brother Evan (Anders W. Berthelsen) and the scorn her older sister Karen (Katrin Cartlidge) still has for her thanks to a secret exposed in their youth. Sarah Polley is very convincing as the repressed young woman whose jealousy is a wicked little mutant squirming to get out and wreck havoc.