Carried out behind closed doors in the confined interiors of an enclosed space, the locked room mystery remains the toughest crime fiction to pull off. Once suicide is ruled out, the question remains: how did the victim expire?

Most locked room mysteries are low-key deduction psychological whodunnits that concentrate on claustrophobic conditions and shabby circumstances, making it difficult to find sympathy for the party involved – oh, they were a drunkard, or asphyxiated in a stupor! But regardless, there’s a dead body.

In director Jaime Collet-Serra’s film, Non-Stop, multiple dead bodies turn up every twenty minutes after text messages demand that the airline transfer $150 million into an offshore account. And with 150 passengers on board, the locked room, i.e. the plane, isn’t hiding the murders but whoever is doing the murders.

The unsympathetic character played by Liam Neeson is Bill Marks, a former cop who has a drinking problem due to his failure to cope with his daughter’s death. As an air marshal assigned to this London-to-New York flight, he comes under suspicion of hijacking the aircraft once it’s learned that the ransom has been deposited in an account in his name.

Challenging the distinction between crime thriller and disaster flick, what emerges is a paranoid pattern where passengers mistrust flight attendants, and thanks to modern technology, everyone observed to be texting or on a computer is suspect!

Initially, the motive looks to be blackmail intended to ruin the reputation of the air marshal, but with bodies taking priority, it’s the tangible links in Non-Stop that put every passenger under Bill’s suspicion. He’s been given the ardent task of keeping a lid on these circumstances to avoid panic, and at the same time conduct a thorough and intrusive investigation of those in coach and business class.

In our PC priority conscious film world, it’s OK to feature an Islamic character to portray the bigotry of the non-Islamic passengers, but of course, they can never be the bad guy behind the threats – so I had to defer to the bias of Hollywood when scrutinizing these characters.

If you follow mystery fiction and its techniques, then obviously things are not what they appear to be. It’s customary for the current suspect more likely than not to be the next victim. Non-Stop plays on both assumptions, leaving Bill the possibility that his investigation is leading to the victimization of passengers. Damned if he does, damned if he don’t!

The two red herrings then become the only two people he trusts on board: a flight attendant and Jen, a passenger who conned her way into the window seat next to him on the flight. They are the only ones who don’t turn on him when in-flight cable news identifies him as a “terrorist.”

The long-term suspects – a New York ex-cop, a schoolteacher, a disgruntled military operative, an international banker – do not measure up in my estimation; they are surrogates for Middle Eastern terrorists. Speculation moves you off mark as in many of the modern detective films; too busy giving their character a complex back-story, the personal interaction between characters distracts from their central purpose: solving murders.

Neeson plays Bill as unromantic, maliciously grounded in doing the job, at odds with superiors. Like searching for a lost plane, the fear is generated by the possibility that with all our technology, it may not be enough to reach a conclusion.

In a long list of past films from ocean liners with their multiple compartments to intercontinental railroads, Non-Stop uniquely takes the idea of a crime in plain sight and meshes it with the locked room murder scene offering alibis for all the usual suspects.

The trick is to watch Neeson, his eyes darting, his mind working overtime calculating the possibilities he might have overlooked. Even locked in a lavatory on a smoke break, his uneasiness foreshadows the inevitable next twenty-minute interval between murders. That’s what separates the suspense film from any standard mystery.