Curtis LaForche (Michael Shannon) lives in small-town Ohio. He has a good job in construction with his best friend Dewart (Shea Wigham), a lovely wife (Jessica Chastain as Samantha) and adorable daughter (Tova Stewart as Hannah). It's a simple life, but it's comfortable: their house is small and tidy, their homewares look like they were inherited from parents and grandparents; Hannah is deaf but responding well to ASL classes. What is there to worry about?

The answer comes soon enough: worry slowly infects the LaForche household when Curtis begins to have bad dreams. Bad dreams that soon become terrifying nightmares: his friendly dog Red bites through his arm; faceless figures smash through his car windows, strangling him as they kidnap Hannah; thick, golden rain falls.

They are among some of the most effective nightmare sequences in memory; stripped of any sense of narrative, which all-too-frequently keeps dream sequences bogged in the mundane, and with deft employment of genre dynamism and expert editing, these moments are terror, pure and simple.

He wakes sweating, choking for air, frightened that these dreams may instead be visions, prophecies. His anxiety only seems to be assuaged by renovating the decrepit tornado shelter in their backyard.  

He visits his mother (Kathy Baker), who lives in an assisted-living facility; she was diagnosed as a paranoid schizophrenic in her 30s. Perhaps, Curtis thinks, that explains it? He borrows books on mental illness from the library and reads them in the tornado shelter. 

Curtis' descent - into madness, underground - recalls Sigmund Freud's portrait of the madman as a dreamer awake. His nightmarish visions begin to infect his waking life: thunderclaps ring out on sunny days, and great flocks of birds cast sinister shadows in the sky. "Is anybody else seeing this?" he asks the night air, Jessica and Hannah asleep in the car, as he watches great swathes of lightning cut the sky in half.

Alongside this, another very real anxiety emerges, as the family face the dread that has settled over much of America: money, or the lack of it. Samantha makes homewares to sell at a market, and stashes the money in a cake tin, dreaming of a summer holiday. Hannah's impending cochlear implant surgery is covered by Curtis' employer's healthcare plan, but the creeping dread remains: what if job and financial security were magicked away?

To describe Take Shelter as overwhelming would be an understatement, though it's not merely hyperbole: it's one of the most accurate and, thus, distressing portraits of anxiety since Vertigo.

(Those who've suffered in the vice-like grip of that disorder could well be advised to avoid the film for fear of relapse; those who've never understood it could do to see Take Shelter as a total immersion virtual reality experience.)

What's striking about Curtis' experience, however, is its multifaceted quality, which is a testament to the joint powers of Shannon and writer/director Jeff Nichols.

Mental illness, seen through the prism of cinema, is too often a simple proposition: people are crazy, or they are sane. Take Shelter explores, with great nuance, the way in which "madness" can descend upon an otherwise capable person, a person who may be at the mercy of their torment one moment and then able to view it in a rational and objective manner the next.

So, Curtis finds himself regularly overwhelmed by dread, but when that subsides he will calmly read books on mental illness and prepare lists of symptoms for a counsellor. Does that mean he is mentally ill but high-functioning, or that he's not ill at all?

The ever-shifting sand of that quandary, for Curtis himself as much as the audience, is what gives Take Shelter its propulsive, unnerving tension, right up to its final ambiguous seconds (an ambiguity that viewers will find either hopeful or desolate; I'm in the former camp).

Take Shelter is astounding. Shannon's performance, calmness spiked by moments of primal terror, is wonderful. Likewise Chastain's portrait of a woman driven by compassion for her husband, which frays almost to breaking point, is heartbreaking; both actors are among the best currently gracing screens. Adam Stone's cinematography and Parke Gregg's editing is impeccable.

This is a film that stays with you for weeks afterward; storm clouds will bring on visions of Shannon's haunted eyes, and you might find yourself looking at raindrops to see if they have turned thick and golden.

Like Curtis, you'll become a dreamer awake.

- five stars

 Take Shelter is in cinemas October 13th.