There’s a reason why the murder mystery has endured as one of the big screen’s most tried and true film genres for more than a century. Like a cinematic magic trick, the truly great whodunnits manage to be both utterly thrilling and truly satisfying—especially when the viewer doesn’t come close to puzzling out the conundrum at the center of the story until the very end. Of course, a well-crafted plot is merely the foundation for a beguiling big-screen mystery. . In order to craft a worthy murder mystery, one that manages to surprise the audience while also playing fair with their expectations, several key ingredients are necessary. As theaters prepare to unspool the latest Agatha Christie film adaptation—Kenneth Branagh’s third turn as Hercule Poirot in A Haunting In Venice—we decided to take a close look at the seven elements needed to craft an engaging, textured whodunnit, the kind of murder mystery that is at once devilish, delightful and deviously concocted.
The location of a murder mystery communicates the mood and tone of the story that’s about to unspool. It provides a keen sense of context—are the characters part of the world depicted, or fish out of water struggling to adapt?—as well as ample opportunities for tension, intrigue, suspense and misdirection. In The Big Sleep, Phillip Marlowe is embedded in Postwar Los Angeles, yet he steps into a wealthier, corrupt, and more shadowy side of the city he knows. The various film versions of the Sherlock Holmes mystery The Hound Of The Baskervilles use the Victorian-Gothic moors to convey a moody air of the supernatural, in sharp contrast to the logic-driven deductive intellect of the famed detective.
The various films based on the works of Agatha Christie tend to use exotic, expansive international locales as a framework to introduce an array of characters from diverse backgrounds; in Murder On the Orient Express that aesthetic is deftly flipped midway through as the story shifts to the claustrophobic environs of the stranded train, where the detective and the suspects are trapped with a killer in their midst. Variations on that theme include The Hateful Eight’s remote snowed-in waystation and Rear Window’s tightly packed apartment complex.
Every homicide at the core of a murder mystery requires a shared investment by both the detective on the case and the audience, and that experience must intensify as the story plays out. Early in Knives Out, crime novelist and family patriarch Harlan Thrombey is vividly depicted as a colorful, charming character beset by his needy progeny who shares a warm relationship with his kind and honest caregiver, Marta. This ensures that viewers will be pulled into the investigation into Harlan’s death, and that they’re hooked by the question of whether Marta can avoid being blamed for his death. Rear Window presents a less-defined victim and killer, and neighbors are observed from afar, until it becomes inescapably clear that “Jeff” Jeffries’ suspicions of foul play are well founded. The inherent voyeurism and the almost claustrophic proximity are so relatable that the audience can’t help but wonder what they might do if faced with the same situation.
Perhaps the most essential ingredient in a truly absorbing cinematic mystery, the detective must be a surrogate for the audience as well as a fascinating protagonist. The sleuth at the center of the story also needs to be a sharply drawn character with unique qualities, quirks and distinctions. An especially well-defined moral code, whatever the gradation, is another neccessity, along with an increasingly personal stake in the outcome. The Maltese Falcon’s private eye Sam Spade feigns detachment, but he’s doggedly determined in his pursuit of the truth. Knives Out’s Benoit Blanc is a well-mannered, famed gentleman detective with eccentric, sometimes showy flourishes. Some detectives seem unlikely in their prowess, like The Mirror Crack’d’s grandmotherly Miss Marple or Fargo’s very pregnant Marge Gunderson; others offer comedic twists on the form, like The Thin Man’s cocktail-swilling sophisticates Nick and Nora Charles, or Fletch’s street-smart, wisecracking investigative journalist Irwin M. Fletcher.
Whodunnits can only keep audiences guessing if there’s a convincing assortment of whos, each with their own motives and opportunities to commit the heinous act at the center of the story. The more vivid and colorfully drawn these suspects are the better. The many films based on Agatha Christie novels—especially the Peter Ustinov and Kenneth Branagh versions of the novelist’s Hercule Poirot tales—work within a template that’s particularly adept at allowing expansive casts of characters to slowly reveal their own reasons to be suspected in the victim’s demise. The apotheosis of this, of course, is Murder On The Orient Express, where literally everyone had a hand in the murder. Knives Out and Glass Onion are, of course, the contemporary heirs apparent to those Christie yarns. And Clue deftly put a hilarious spin on the classic board game’s ensemble of characters where anyone—depending on which version of the film’s multiple endings you’re watching—may have done the deed.
It’s the storytelling sleight-of-hand that often jolts the detective—and/or the audience—out of complacency. Just as they think they’re on the brink of solving the central mystery, they realize they’ve been wandering down blind alleys. Psycho is a textbook model: by all appearances the killer is Norman Bates’ domineering mother, until the true identity of the murder is revealed in all its complex psychological glory. The Usual Suspects is, famously, almost entirely an ingenious misdirect where the entire series of events is revealed to be expertly spun by a very unreliable narrator.
As opposed to the “ah-ha” effect of red herrings, the mid- and late-act plot twists are intentionally designed to be jaw-droppers, forcing the protagonist and the audience to reconsider and reframe everything they thought they knew. The film noir Laura provides a seminal example of a seemingly out-of-the-blue but cleverly set up curveball when the murder victim suddenly turns up very much alive; Gone Girl, Vertigo and The Third Man offer variations on the theme. Conversely, Glass Onion sets viewers’ heads spinning with its one-two punch of reveals regarding the secrets of Andi Brand’s true identity and the actual reason for Benoit Blanc’s presence at a billionaire’s private island.
By the end, all the puzzle pieces of plot and character need to not only fit neatly and logically together, the audience needs to leave feeling like they’ve arrived at a meaningful end, and that their journey has been engaging both cerebrally and emotionally. Memento finally resolves all of its enigmatic twists and turns with a clever, surprising resolution that also reflects and explains protagonist Leonard Shelby’s fractured psyche; in Rear Window Jeff doesn’t just successfully flush out his homicidal neighbor, he realizes that, in both crime-solving and in life, his girlfriend Lisa is a perfect partner. Even as the murder mystery that sparked L.A. Confidential’s many knotty, intertwining plotlines fades to the background, the gray-shaded characters—good, bad and in between—arrive at appropriate endpoints they’ve earned along the way. Of course, a satisfying conclusion doesn’t always mean a happy one: ambiguous, ambivalent, even unsettling endings, like those featured in Chinatown, Basic Instinct and Zodiac, can feel perfectly emblematic, in terms of the shadowy mood and nihilistic tone, of the plots that unfolded on the screen.