Rožat "Rusty" Sabich, a Kindle County prosecutor and co-worker of Carolyn, is assigned her case by his boss, district attorney Raymond Horgan.
Horgan is currently losing his re-election campaign against Nico Della Guardia, an old protege turned rival, and informs Rusty that his continued employment is entwined with Raymond's victory, which he believes hinges on finding and convicting Carolyn's killer.
Despite his obvious conflict of interest, Rusty takes charge of the investigation but makes clumsy attempts to divert its areas of inquiry away from the DA's office, and by extension himself.
Throughout the novel he reflects on various relationships in his life: with his late father, a closed-off, angry man; with Nico, a friendship that soured due to uncontrollable circumstances; with Barbara, a volatile mixture of devotion and disdain; and Carolyn, which he has struggled to define since its end.
Horgan loses the election and, within days of taking office, Nico charges Rusty with Carolyn's murder, encouraged by his overzealous deputy, Tommy Molto.
Sandy, while subtly threatening Lyttle with his own knowledge of this, is able to discredit a forensic expert's testimony regarding the sperm sample and inconclusive witness statements, persuasively arguing that Tommy, who was aware of the bribery scheme but not involved, has fabricated evidence to frame Rusty out of misguided loyalty to Carolyn.
When she announces her intention to leave him and take their son, Rusty explains his deduction that she killed Carolyn, as revenge on the woman who nearly destroyed her family; she admits that he is correct.
Nico, his reputation destroyed by the trial, loses a recall election and Rusty is appointed to finish out his term, although his career prospects beyond that are uncertain.
He wonders what led him into the affair which ultimately caused everything to happen, and concludes it was an attempt to escape the existential crisis that has plagued him most of his adult life, even if what she offered him was never more than a fantasy.