Deus ex Machina in thrillers: Clever shock or lazy reveal?

A whodunit unfolds. A crime is committed, a detective is pressed into action, and the audience is invited to follow the clues, examine the evidence, and try to crack the case alongside the investigator. Naturally, the solution must emerge from hints scattered throughout the story.
But then the moviemakers decide to play smart. The culprit turns out to be a completely new character—someone with no connection to the plot so far. No one could have seen that coming because the story never gave them the chance.

This kind of narrative twist is known as Deus ex machina—a plot device where an unsolvable problem is abruptly resolved by an unexpected and improbable event, often through the sudden appearance of a new character, skill or object that hadn't been introduced or foreshadowed earlier. It’s often considered lazy writing, especially in mysteries and thrillers, as it violates the unspoken contract between storyteller and audience.

A similar twist plays out in the Malayalam film 'Detective Ujjwalan', featuring Dhyan Sreenivasan in the lead and directed by Rahul G and Indraneel GK.

Spoiler alert: Stop reading now if you haven’t watched the film yet.

While many appreciated the film’s pacing and buildup, the climax left several viewers disappointed. The issue lies in its use of ‘unfair play’—the resolution doesn’t logically follow the clues presented. The reasoning behind the reveal also feels unconvincing, making it harder for the viewer to stay emotionally or intellectually invested.

When the culprit is finally revealed in 'Detective Ujjwalan', the immediate reaction is: “Who is this person, and where did he come from?” It feels disconnected—almost as if the backstory was retrofitted to serve the twist. The payoff falls flat because the audience was never given the chance to suspect this character. Throughout the film, viewers are encouraged to follow red herrings, examine suspects, and piece together clues—only for all of it to amount to nothing. That’s where the flawed use of Deus ex machina breaks the experience: it undermines the mystery and alienates the audience.

Interestingly, several acclaimed films have employed this same device—but to brilliant effect.

Take 'The Usual Suspects', directed by Bryan Singer. The story is told by Verbal Kint, a quiet, nervous man recounting a complicated series of events involving a shadowy figure named Keyser Soze. In the final moments, we discover Verbal is Soze, and everything he said was a lie—crafted from items lying around the police station. The twist completely redefines the film. It may come out of nowhere, but it feels earned because it’s executed with such finesse. It rewards the audience with a new lens on everything they’ve seen so far.

Take 'Oldboy', directed by Park Chan-wook — a film where the protagonist spends years unravelling the mystery behind his shocking 15-year imprisonment. In the end, the villain reveals he hypnotised Dae-su and manipulated him into a relationship with his own daughter as revenge. There’s no way Dae-su could have figured this out through clues—it’s a pure reveal. Yet, it works, because it aligns with the film’s haunting themes of revenge and psychological torment. The twist doesn’t just shock—it deepens the narrative’s emotional impact.

These examples show that Deus ex machina isn’t inherently bad—it all depends on execution. In The Usual Suspects and Oldboy, the twist arrives suddenly, but it reinforces the story’s core ideas and feels thematically justified. It redefines the narrative without betraying the viewer’s investment.

In contrast, 'Detective Ujjwalan' introduces a twist that the audience was never equipped to anticipate. It breaks the narrative contract and leaves viewers feeling misled, not surprised.
Ultimately, in crime thrillers, the most satisfying twists aren’t just unexpected—they’re meaningful. They’re built on foundations laid from the very beginning.