Unger builds her mystery around the geography of Heart Island, a remote family enclave in the Adirondacks, where matriarch Billie Burke dominates her husband, son and daughter with an aggressive, critical personality. While husband Joe elects to spend a few days in the city during the annual visit and son Theo refuses even to attend, Kate is not as fortunate, anxious to tell Billie the news about her upcoming novel before the book’s release. Kate’s novel is based on the accumulated dairies of her grandmother, Lana, and her aunt Caroline, handwritten volumes documenting the family’s intimate history—including Lana’s infidelity with a longtime lover on a nearby island.
At the last minute, only Kate, teenaged daughter Chelsea, and Chelsea’s friend Lulu set out for Heart Island. Second husband Sean is held back on business, along with younger son, Brendan, who has a painfully sprained ankle. Billie and Kate will share an emotional reckoning of sorts, Billie facing some difficult truths as her daughter announces her imminent success as a writer, the mother’s vulnerabilities exposed as differences push mother and daughter farther apart: “If ever there was a place that needed an exorcism, it was Heart Island.” As nature threatens the island with the ferocity of an approaching storm, fate orchestrates a collision with outside forces that leaves the women on Heart Island in great danger, aware of how precious life is when threatened.
Meanwhile in New Jersey, a waitress named Emily is forced by her lover Dean and his former acquaintance, Brad, to rob the restaurant where a thoughtful owner has befriended the shy, lonely girl. With one dead and another in a coma after the robbery, the trio flees toward Heart Island, a place Emily has dreamed of since childhood, believing herself a part of its long history. The robbers argue, and a violent Brad terrorizes Emily and Dean, who knows what his partner in crime is capable of. Emily clings to an absurd romantic notion that Dean isn’t as hopeless as he appears. In reality, Emily is the weakest of the three, a victim of her own self-delusions, rationalizing a chronic habit of bad choices.
Arriving at the island with hopes of finding cash and jewels in a bunkhouse safe, the intruders spread mayhem and murder along every step of the journey. They are as careless in assaulting the mountain terrain and family home as in every aspect of their adventure: clumsy, violent and stupid. The emotional confrontation between Billie and Kate pales in comparison to their immediate danger from the intruders. As thunder crashes around them, the intruders act out their ill-planned maneuvers, unleashing a chain of events that destroys everything Billie holds dear. Her beloved Heart Island stands as a lonely citadel, with few to care about the woman who clings to her rocky domain as a substitute for happiness.
Unger accomplishes all with her stylistic energy, creating interesting if flawed characters in the various Burke family members. However, Emily is a weak and uninspiring personality, a victim too frightened by life to have convictions let alone stand for them, an issue that ultimately takes some power out of the thriller. Overall, though, Unger delivers. Heartbroken makes a compelling foray into a family riddled by dysfunction, rallying in the face of threat.