Director/Writer: Woody Allen
Starring: Joaquin Phoenix, Emma Stone, Parker Posey
Theatrical release: 11 September 2015
“I’d still let him take me to Spain.”

Aspiring assassins and Agatha Christie wannabes take note: “the perfect murder” must also factor in an element of existential fulfilment for the killer. That’s the theory proposed in Irrational Man, Woody Allen’s introspective, occasionally funny detective caper about finding meaning in life by taking away someone else’s.

From Crimes and Misdemeanours to Match Point, Allen has regularly philosophised the act of murder, which manifests itself in a protagonist bordering on self-parody. Abe Lucas (Joaquin Phoenix) is a neurotic philosophy professor, professional writer, amateur murderer, and dater of a younger woman. Regarded as prolific on the page and between the sheets, but unsatisfied with life, Abe juggles romantic affairs on campus with science tutor Rita Richards (Parker Posey) and fangirl student Jill Pollard (Emma Stone). Reluctant to their advances, he can’t shake off a duo of eager women verbalising a few “you’re a genius” remarks to emphasise their attraction. So far, so Allen.

But Phoenix makes the role his own, offering more menace and vulnerability than Allen’s typical surrogates, as seen when Abe literally plays Russian roulette; recklessly swigging from a bottle while twirling a pistol, he’s more than just a moody guy with one-liners about Dostoyevsky. Neither does he mimic Allen’s mannerisms; murmured lines echo the character’s ongoing anxiety, without stuttering for comic effect. The same applies to Posey and Stone, who both inject zip and colour captured by Allen’s now regular DP, Darius Khondi.

What revitalises Abe’s life isn’t the May/December relationship (as everyone guessed from the casting and misleading trailer) but eavesdropping in a café to a woman on the verge of losing custody of her children because of an immoral judge. Presupposing he would never be suspected of the crime, Abe speculates to Jill that he could perform a murder of behalf of a stranger, and thus twist it into an act of charity. Secretly following through with the plan, Abe’s mojo is replenished and his existential crisis is solved, as oddly proven by ordering larger breakfasts. “This is the meaningful act I was searching for,” he admits without irony. Out of Phoenix’s mouth, it borders on profound.

There’s a snag. Just as nobody was fooled by Phoenix’s famed bearded appearance on Letterman, Abe leaves behind a trail of blood-stained breadcrumbs that trigger Jill’s suspicions – mostly because she was right there when the plan was hatched. What follows is a Woody Allen episode of Columbo with Emma Stone as the detective, wrestling with the dilemmas of whether Abe was correct in his behaviour, if misguided altruism deserves a prison cell, and why she’s always stuck in roles about age-gap romances.

The central murder – involving poison, coffee, and hoping someone has dodgy peripheral vision – is so preposterous, it’s when Irrational Man slides into fun mode. The ineffectual Kierkegaard and Dostoyevsky namedrops of the first act later become punchlines for their clichéd nature: the image of a troubled murderer annotating a copy of Crime and Punishment belongs to a New Yorker cartoon. It also helps that a recurring music cue, “The In Crowd” by the Ramsey Lewis trio, instils a bristle lightness throughout, even if it’s unintentionally maddening to hear the same jazz ditty every few minutes.

Somehow smarter and stupider than the plot suggests, Irrational Man is an entertainingly twisty romp that turns to comedy instead of fully delivering on its philosophical promise. After raising questions of life and death, the story unfolds with throwaway silliness like Jill discovering Abe’s Crime and Punishment conveniently has the deceased victim’s name pencilled in the margins. That’s the sign of a filmmaker who’s spent a lifetime striving to crack life’s greatest ethical mysteries, but finds only humour in the void.

Rating: 7/10

Out in UK cinemas: 11 September