Kevin Pace, a 56-year-old painter, has spent years working on a massive secret painting, 12 feet high and over 21 feet across, housed in a locked building on his property. No one is permitted to see it: not his wife Linda, not his children April and Will, not even his best friend Richard, a retired Beowulf scholar who has promised to burn the studio if Kevin dies first. Kevin produces other canvases in a separate studio, works he dismisses as "whores" made to be sold, but the secret painting is different, saturated with phthalo blue, Prussian mixed with indigo, cerulean bleeding into cobalt. The novel braids three timelines to reveal why that painting exists and what it holds.
Ten years before the present, Kevin and Linda travel to Paris to celebrate 20 years of marriage. When Linda leaves to visit a friend in Bordeaux, Kevin attends a lecture on Eugène Boudin's cow paintings, where his hand grazes that of Victoire, a 22-year-old aspiring watercolorist studying at the
École des Beaux-Arts. She is direct, witty, and openly flirtatious. They have coffee and part with plans to meet again. Kevin tells Linda about the encounter that night; she responds warmly. He reflects that he was still innocent when he hung up, and yet he was not.
Thirty years earlier, in 1979, Kevin and Richard are 24-year-old graduate students at the University of Pennsylvania. Richard's older brother Tad, whom the family calls "Fup" (the fuckup), has a history of drug problems, jail time, and self-destructive behavior. When Tad vanishes for seven months and is reported heading for El Salvador, Richard asks Kevin to help find him. They fly to Ilopango Airport and are connected with a man called the Bummer, a profane, racist, self-described Vietnam veteran and mercenary who agrees to locate Tad for $1,000.
In the present, Kevin reflects on the painting's origins. He recalls a summer on Martha's Vineyard when his son Will capsized their canoe in excitement over a fledging osprey while April receded quietly into the background. That night, moved by April's insecurity, Kevin created a small canvas called
Fledgling Blue, which became the seminal image for the large private painting. He admits privately that he lied to Linda about when he fell in love with her. A period of heavy drinking has crept up on him, starting with midday wine and graduating to scotch. His stopping comes not from a single epiphany but from slow-growing disgust; he quits cold turkey, replacing alcohol with obsessive work on the secret painting.
In Paris, the affair escalates. Victoire brings Kevin to her flat, where a first kiss leads to undressing. Kevin pulls back and leaves to meet Linda's arriving train, telling his first lie. He then tells a larger one, suggesting his French gallerist wants him to stay two more weeks. Linda agrees, joking about his "new girlfriend." Over the days that follow, Victoire reveals a stunning abstract watercolor, green leaning into blue, unlike any of her conventional work. Kevin weeps at the sight of it. When Victoire's mother Sylvie asks directly if Kevin loves her daughter, he surprises himself by answering yes. Richard, arriving from London for Kevin's gallery opening, deduces the affair and tells Kevin the relationship has no future. Kevin acknowledges he must break Victoire's heart.
The Bummer leads Kevin and Richard into the Salvadoran mountains, armed with an M16 and a .45 pistol. On the second day, they come upon a village where soldiers have committed an atrocity. The body of a young girl lies in the middle of a muddy road. Her father and a small boy emerge from a shack. Kevin and Richard dig a grave. As they fill it, the boy, whom Kevin privately names Luis, brings Kevin his dead sister's severed hand, lost in the mud. Kevin drops it into the grave before anyone else notices. The cobalt blue of Luis's shirt becomes an indelible image that feeds the private painting.
At a mountain cantina, they encounter Carlos, a Dutch man who carries a notebook of Polaroid photographs of dead people and charges grieving families to view them. The Bummer leads the group to a lakeside Nicaraguan drug operation where Tad is working. Richard breaks cover and runs to his brother. A confrontation erupts and the group flees under fire. The Bummer hands Kevin his .45, then is struck by a bullet and killed. Kevin, Richard, Tad, and Carlos escape in the Cadillac.
In the present, April, now 16, tells Kevin she is pregnant and swears him to secrecy. Kevin agonizes over the promise. He consults Richard, who frames the dilemma as two irreconcilable obligations and concludes Kevin is "fucked." Kevin delays telling Linda.
Left alone with the car in San Salvador, Kevin begins burning Carlos's notebook. A Salvadoran soldier appears and fires at him. Kevin turns with the .45, and the gun goes off, killing the soldier instantly. He registers the man's light-blue socks, the blood on the wet sidewalk, his useless plea for the dead man to get up. On the plane home, he tells Richard, who calls it self-defense. Kevin replies, "I was supposed to be in Philadelphia." This killing becomes the secret Kevin carries for 30 years. He confides it to Victoire during an intimate conversation in Paris; she shares that she once attempted to take her own life. She tells Kevin she knows he cannot leave his children and harbors no illusions about their future.
April's secret collapses when she has a miscarriage. Kevin is about to tell Linda when April, bleeding and feverish, reveals the pregnancy herself. Linda is furious. April is also angry, realizing Kevin was about to break his promise. Linda shuts Kevin out, takes over April's care, and asks: "If you could keep something like this from me, what other secrets are you hiding?"
The Paris affair ends when Will falls ill and Kevin flies home early. Victoire comes to his hotel, tells him she loves him, and says she knows she will never see him again. They hold each other, too sad to make love, and part.
Kevin decides to return to El Salvador to confront his past. He tells Linda he needs to take a trip; she says she has always known something happened there. In Las Salinas, the village where the girl was killed, Kevin encounters a young local woman named Betty who speaks English and serves as his guide; she takes him to the home of Emberto Rodriguez, the girl's father, who embraces Kevin and cries. Kevin meets Emberto's son Arturo, the boy he once called Luis, now in his thirties. Betty leads Kevin to the grave, where he learns the girl's name, Lavada, for the first time. Walking the streets of San Salvador before dawn, Kevin approaches the site of the killing but finds his need to revisit it has dissolved. He hears Linda's voice telling him he is a good man. He confronts a deeper truth: He married Linda without loving her, but he now recognizes that he has always loved her.
Kevin returns home to find the children away and Linda cleaning the kitchen. She tells him she has been angry for years, not just about April but about his perpetual absence. Kevin listens, then takes her by the hand and walks her to the locked shed. He tells her he should have let her in a long time ago. He unlocks the door, lets her enter first, and switches on the lights. Linda stands before the enormous canvas. "So much blue," she says. "So much blue." Kevin responds, "Now you know everything."