The Unreliable Narrator: How to Heighten Suspense and Keep Readers Guessing in Psychological Thrillers

By Carol Willis

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One of the most powerful tools in a psychological thriller is the unreliable narrator—a character whose perception, memory, or understanding of reality is compromised. This technique pulls readers deep into the mind of the protagonist while simultaneously keeping them at a distance, sowing doubt and suspicion. When done well, it heightens tension and fuels page-turning suspense.

In psychological thrillers, the unreliable narrator isn't just a stylistic choice—it's a structural engine. First-person narration lets readers experience the character’s inner turmoil, but what happens when that narrator cannot be trusted? Whether the cause is head trauma, substance abuse, mental illness, or sheer denial, the effect is the same: uncertainty. 

And uncertainty is the lifeblood of suspense.

What Makes a Narrator Unreliable?

Unreliable narrators are those whose version of the story is distorted by deception, delusion, or impairment. Some lie deliberately; others mislead unintentionally due to mental illness or altered states of consciousness. In psychological thrillers, the latter are especially compelling. These narrators believe what they say and yet the reader comes to understand that what they believe may not be true.

Let’s take a closer look at how several authors, Annie Ward in Beautiful Bad (2018), Tana French in The Witch Elm (2018), and Imran Mahmood in I Know What I Saw (20210) use head trauma, addiction, and psychological instability to create deeply unreliable perspectives that drive suspense and emotional tension.

Head Trauma as a Narrative Device

Set in the American Midwest, Annie Ward’s Beautiful Bad is a tightly constructed domestic psychological thriller centered on Maddie, a devoted wife and mother, her war-scarred husband, and their young son. As is typical of the genre, nothing is as it seems: buried secrets and simmering tension culminate in a shocking murder. During a camping trip, Maddie suffers a traumatic brain injury that leaves her memory fragmented. Much of the novel hinges on her attempts to piece together what really happened. Ward structures the story through short, staccato chapters and a nonlinear timeline that mirror Maddie’s cognitive disorientation. She also weaves in her husband’s PTSD and alcoholism, which amplify the emotional instability and deepen the atmosphere of dread. Readers are drawn into a fog of partial memories and unreliable perceptions, forced to navigate Maddie’s fractured psyche in search of the truth.

Tana French’s standalone psychological suspense, The Witch Elm offers a more introspective, character-driven psychological thriller, where trauma fractures not only memory but identity. Toby, a privileged and affable young man, survives a brutal home invasion that leaves him with a severe head injury and a lingering sense of cognitive instability. As he retreats to his family’s ancestral home to recover, a skull is discovered in the garden, triggering both a police investigation and a deeper unraveling within Toby himself. French masterfully entwines the external mystery with the internal one: who was Toby before the attack, and can he trust the person he is now? The narrative blurs the line between guilt and innocence, perception and denial. Toby’s unreliable memory becomes the novel’s engine of suspense, compelling readers to question not only what happened, but whether Toby himself might be capable of violence he can no longer remember.

Imran Mahmood’s I Know What I Saw (2021) offers another powerful example of how head trauma can fracture both memory and identity. The narrator, Xander Shute, is a once-successful barrister now living on the streets of London. When he accidentally witnesses a murder in what he believes is a break-in gone wrong, he reports it only to be told by police that no such crime occurred, and the apartment is occupied by a completely different couple. What follows is a tense unraveling of Xander’s mind. His past trauma, mental health struggles, and head injuries blur the line between what he remembers and what may have never happened at all. Mahmood uses fragmented memories, dreamlike logic, and time slippage to keep the reader guessing: Is Xander witnessing a conspiracy, or is he caught in the spiraling aftermath of untreated trauma? His voice is sharp, intelligent, and self-aware. Yet the more he insists on what he saw, the more readers question whether they should believe him.

Other Forms of Unreliability

Substance abuse is another common and highly effective device in thrillers. Alcoholism and drug addiction introduce uncertainty, distortion, and mistrust—the perfect ingredients for narrative suspense. These altered states skew perception, bend time, and create memory gaps that leave both the character and the reader struggling to connect the dots. In Paula Hawkins’s The Girl on the Train (2015), for example, blackouts erase entire chunks of the protagonist’s experience. The narrator becomes both detective and suspect, trying to solve a mystery she might have unwittingly caused.

Mental illness—especially dissociation, anxiety, and PTSD—can also destabilize a narrator’s grasp on reality. A character may be telling the truth as they see it, but that version of events is filtered through trauma, fear, or delusion. These internal fractures not only add emotional complexity but also keep readers questioning what’s real, and what’s imagined.

Why It Works

Unreliable narrators heighten suspense by withholding clarity. In a genre driven by twists and revelations, these characters provide fertile ground for ambiguity. The reader doesn’t simply ask, "What will happen?" but, more compellingly, "What is really going on?"

Unlike thrillers that rely solely on external threats, psychological thrillers with unreliable narrators turn the narrative inward. They make the protagonist’s mind the true battleground. The suspense comes not only from what the character might do, but from whether they even know what they are capable of.

For Writers: Using Unreliability to Build Suspense

Start with character: What might your protagonist be unwilling or unable to see clearly? Consider layering trauma, denial, or dependence on substances to introduce narrative distortion.

Use memory loss or selective recall to reveal truths in increments. Structure scenes around flashbacks, contradictions, or moments where the narrator second-guesses themselves. Let your setting mirror the character’s instability—fog, rain, locked rooms, or chaotic domestic spaces can reinforce psychological disarray.

And most importantly, root the unreliability in emotional truth. Readers don’t need to trust your narrator to follow them—they just need to believe in their struggle. Suspense thrives in this space between belief and doubt.