A Serial Killer’s Guide to Marriage Summary, Characters and Themes

Asia Mackay’s A Serial Killer’s Guide to Marriage is a razor-sharp, genre-blending novel that explores the collision of domestic life and moral chaos through the lens of a feminist antihero. 

At its core is Hazel, a former vigilante killer turned stay-at-home mother, who finds herself suffocating under the weight of nappies, playdates, and repressed rage. As old instincts stir and justice calls once more, she and her husband—also no stranger to blood—must decide whether their idyllic family life can coexist with the darkness that still simmers beneath. It’s a darkly funny, propulsive tale of love, motherhood, violence, and identity.

Summary

Hazel, known as Haze, appears to be living a perfectly ordinary life as a suburban mother and wife. She attends music classes with her toddler Bibi, makes polite conversation with other mums, and tries to be content. 

But her internal monologue reveals the truth: she used to kill bad men. Fourteen, to be exact. Her targets were abusers, predators, and monsters society let slip through the cracks. 

Each kill was a reclamation of power—until she gave it up for a chance at peace with her husband, Fox, another former killer who now toils in finance. Domesticity, however, has not been kind to her identity.

Haze befriends Jenny, a single mother escaping an abusive relationship with a man named Bill. While Jenny tries to rebuild her life, Haze becomes increasingly involved, obsessed even, especially when she learns that Bill is thriving and unpunished. 

As her instincts awaken, Haze begins investigating him, collecting evidence in secret. Fox notices the shift and tries to warn her off, but Haze is no longer satisfied with quiet righteousness. 

When Bill retaliates against Jenny legally and personally, Haze is pulled even deeper into a path she once left behind.

As tensions escalate, Haze and Fox’s marriage frays. Their shared history—once thrilling—now feels dangerous in the context of parenthood. Fox seeks therapy, questions their choices, and plans for contingencies. 

Meanwhile, Haze unearths new evidence against Bill, including a history of violence swept under the rug. When Jenny’s son is nearly harmed and Bill continues his psychological warfare, Haze retaliates—not by killing him, but by strategically dismantling his life. 

She sends anonymous tips to his employer and girlfriend, exposing his secrets. He’s suspended, dumped, and publicly shamed. But the retaliation isn’t enough. Haze still itches for more.

Eventually, Bill confronts Jenny at her home. Haze intervenes violently—but stops short of murder. 

The incident sends ripples through her relationships. Jenny, once a friend, becomes afraid. Fox, desperate to protect their daughter, suggests leaving or taking the fall if Haze is caught. Haze feels isolated, uncertain, yet newly empowered. Her sense of justice is reignited, but the cost—emotional, familial, existential—grows heavier.

In the aftermath, Haze attempts to pause. She paints again, channels her rage through art, and tries to return to domestic quiet. 

But it doesn’t last. 

A letter arrives—an anonymous threat. Someone knows who she and Fox really are. The sender is Gideon, a man they once spared. He offers a deal: help him eliminate a target, or he exposes them.

The target is a trafficker, a monster worse than Bill. 

Haze is invigorated; Fox agrees reluctantly. Together, they plan and execute the mission with chilling precision. The kill reawakens old feelings and passion between them, as if violence was their native language. But Gideon returns with more demands, implying they are now in his pocket.

Fox proposes a new code: if they must kill again, it should be ethical, targeted, and controlled. Haze agrees—but deep down, she knows she’s fully back. This is who she is. 

The story ends with Haze and Fox in the woods, reenacting a ritual fight, their knives gleaming in the moonlight. It’s not a battle; it’s a renewal of vows. Their love is violent, messy, and eternal. Till death do us part isn’t a threat. It’s the promise they live by.

Characters

Haze (Hazel)

Haze is the protagonist whose internal conflict lies at the heart of the story. Initially presented as a seemingly ordinary mother, Haze hides a violent past and a deep-seated longing for autonomy and control, which she once found in her killing spree framed as acts of feminist justice.

As a wife and mother, she struggles to reconcile her violent instincts with her domestic life, feeling suffocated by motherhood and her marriage to Fox. Throughout the narrative, Haze is confronted with the tension between her old identity and her current role, leading to a series of moral dilemmas.

Her actions, although motivated by a desire to protect those she loves, reveal a woman teetering on the edge of her darker desires. Despite her violent tendencies, Haze’s love for her daughter, Bibi, grounds her and keeps her from fully embracing her past life as a killer, even as she is pulled back into it.

Fox

Fox is Haze’s husband, and his character adds complexity to the themes of love, justice, and self-control. Like Haze, Fox has a violent past, but his commitment to his family and domestic life keeps him from fully embracing his darker instincts.

As the story progresses, Fox becomes more aware of Haze’s struggle and the cracks in their marriage. His desire to protect their family and keep their past buried often clashes with Haze’s growing need to return to her violent ways.

Fox’s internal struggle is primarily driven by his love for Haze and his fear of losing her to her darker impulses. He finds himself in the difficult position of trying to preserve the stability of their family while dealing with the consequences of their violent past.

Jenny

Jenny is a crucial secondary character in the story. She is a single mother who initially befriends Haze and becomes a confidante.

However, as the plot progresses, Jenny’s role becomes more significant when Haze decides to take matters into her own hands to protect her from her abusive ex, Bill. Jenny represents vulnerability and the complexities of women’s relationships with men, as she becomes the object of Haze’s protective instincts.

Over time, Jenny grows wary of Haze’s true nature, as she begins to suspect that her friend’s actions go beyond mere support and veer into something darker. Jenny’s evolving relationship with Haze highlights the tensions between loyalty, fear, and self-preservation.

Bill

Bill is the antagonist who embodies the abusive, misogynistic figures that Haze seeks to punish through her vigilante actions. While he initially appears as a minor threat, his role in the story escalates when Haze becomes determined to expose his past crimes and protect Jenny from further harm.

Bill’s manipulative and violent behavior towards Jenny sparks Haze’s need to take justice into her own hands. As the plot progresses, Bill becomes a symbol of the oppressive patriarchal forces that Haze wants to destroy, and his presence in the narrative acts as a catalyst for Haze’s return to her darker self.

Bibi

Bibi, Haze and Fox’s young daughter, represents innocence and the future that Haze is trying to protect. Throughout the novel, Bibi is an anchor for Haze, grounding her in the love of motherhood, even as Haze struggles with her violent impulses.

However, Bibi’s presence also highlights the stakes of Haze’s actions. Every time Haze contemplates returning to her violent past, she is reminded of the risks she poses to her family, especially her daughter.

Bibi serves as a symbol of Haze’s internal conflict—her desire to protect her family and her uncontrollable need for autonomy.

Themes

The Complex Dynamics of Power and Control in Relationships

A Serial Killer’s Guide to Marriage deals with the intricate balance of power and control within relationships, especially in the context of marriage. This theme is explored through Haze and Fox, a married couple whose past actions as vigilantes challenge conventional norms of love, loyalty, and partnership.

From the beginning, Haze is portrayed as someone who struggles with being confined by the roles of wife and mother, feeling an overwhelming loss of autonomy. Her violent past provides a sharp contrast to the mundane reality of family life.

As the narrative unfolds, the theme of power becomes even more prominent, especially when Haze contemplates returning to her past life of vengeance. Fox, too, navigates his internal battle between maintaining control over his family and confronting the threat posed by Haze’s uncontrollable urges.

The tension between their desires for stability and the allure of violence becomes a key force in their relationship, pushing them to examine the boundaries of love, safety, and mutual respect. This theme of power and control is further complicated by the arrival of external forces, such as the investigator Gideon, who brings a new layer of manipulation and choice into their lives.

The Consequences of Trauma and Emotional Repression

Another significant theme that runs throughout the story is the lasting impact of trauma and emotional repression. Both Haze and Fox have been shaped by their violent pasts, and their emotional struggles are central to the unfolding of the plot.

Haze’s past, particularly her traumatic childhood and the loss of her close friend Matty, has deeply affected her emotional and psychological state. Her violence, which she initially frames as acts of justice, is deeply tied to a need for control and a response to the trauma she has faced.

The impact of this trauma on her relationship with Fox is palpable, as their marriage becomes a battleground where Haze’s repressed emotions and past actions continually surface, threatening to unravel their family. Fox, too, has been shaped by his past, though in a more subdued way.

His emotional repression is linked to his desire to protect his family, but his inability to fully confront his own past and his growing concern about Haze’s actions create a sense of dissonance between them. As both characters wrestle with their inner demons, the theme of trauma and emotional repression becomes a lens through which the narrative explores the complexities of identity, guilt, and the difficulty of moving forward from a violent past.

A Fine Line Between Right and Wrong

The theme of morality and the fine line between justice and revenge is explored through Haze’s actions and decisions throughout the novel. Initially, Haze’s violent acts are framed as necessary forms of vigilante justice, aimed at punishing those who have wronged others.

However, as the story progresses, the moral clarity of her actions becomes increasingly murky. Haze’s desire for vengeance is juxtaposed with her maternal instincts and her role as a wife, creating a conflict between her sense of justice and her family’s need for safety.

This theme is also explored through the character of Bill, whose abusive actions spark Haze’s return to her violent ways. The novel raises important questions about whether acts of revenge can ever be justified, or if they are merely a reflection of personal rage and unresolved trauma.

As Haze plans her next steps, she continuously grapples with the consequences of her actions and the moral implications of her choices. Her struggle with the ethics of revenge, and whether it is ever truly justifiable, forms a critical part of the narrative’s exploration of justice in a world where right and wrong are not always clear-cut.

The Role of Identity and Self-Realization in Defining One’s Purpose

The theme of self-realization and the quest for personal identity is central to Haze’s character development throughout the novel. Haze’s journey is not just about balancing her roles as a wife, mother, and vigilante; it is about reclaiming her sense of self in a world that seeks to define her by external expectations.

In her past, she found power and a sense of purpose in her violent acts, which she justified as a means of achieving justice. However, as she settles into domestic life, she begins to feel the suffocating constraints of motherhood and marriage, which stifle her true identity.

Haze’s internal struggle between the woman she once was and the woman she is trying to become is a key part of her emotional journey. Her interactions with Fox and Jenny serve as reflections of her own desires for freedom, autonomy, and self-expression.

Over the course of the novel, Haze is forced to confront who she truly is, with all the complexities of her violent past, her maternal instincts, and her need for control. This theme of self-realization culminates in her eventual decision to return to the life of vengeance, suggesting that, for Haze, her identity is inexorably tied to her violent past and the pursuit of justice on her own terms.

The Illusion of Domesticity and the Struggle for Individual Freedom

The tension between the desire for domestic peace and the yearning for personal freedom is a recurring theme in the novel. Haze’s journey reflects a deep conflict between her desire for a stable family life and her need for personal liberation, a theme that explores the illusory nature of domesticity.

As a mother and wife, Haze feels constrained by the mundane responsibilities of daily life. Her violent past, which she once embraced as a form of self-expression, now seems incompatible with the passive roles she plays within the family. This creates a deep sense of dissatisfaction and a desire to break free from the confines of motherhood.

The tension in her marriage with Fox highlights this struggle, as he longs for stability and domestic tranquility, while Haze craves the freedom to act on her instincts, even if it means returning to a violent past. The novel explores how domestic life can often feel stifling for individuals who have been shaped by trauma or who possess a deep need for autonomy, leading them to question the price of conformity and the cost of freedom.

This conflict plays out against the backdrop of Haze’s evolving relationship with Fox, who represents both the safety she seeks and the prison she feels trapped in.