THE one-man show, a staple of theater, tends to be less welcome on the big screen.
Box-office numbers indicate that you didn't want to see Robert Redford alone on a boat in "All is Lost," and you didn't want to see Ryan Reynolds in that coffin in "Buried."
You consented to see Sandra Bullock in a space capsule in "Gravity," but only because you knew that George Clooney popped in from time to time.
Which brings us to "Locke," comprising 86 minutes of Tom Hardy in the cab of a BMW.
I highly recommend it, with the caveat that movie critics tend to like these cinematic experiments more than normal human beings do.
There's a tightroper's daring to movies like "Locke," the way they go against the grain of blockbuster-ism - in this age of 3-D/FX, here's a story set in one place, inhabited by one actor.
It helps that the actor is Hardy, a versatile fellow best known as Bane in "Batman" - one of the franchise's best villains, though he worked without the advantage of a visible face or an intelligible voice.
He's emerging as the movie's most famous chameleon - I didn't recognize him in "Warrior," and left the theater wondering where the producer found an MMA guy who could act.
Here, he takes on yet another new look - a scruffy beard, Welsh accent - to play the title character, an ultra-competent construction manager who has suddenly (or so it seems) come unglued.
We understand, in the opening moments, that he's leaving his work site on the eve of the massive project's most crucial stage.
The mystery of his sudden retreat is doled out in bits and pieces, as Locke talks to his wife, children, subordinates and bosses via a hands-free device.
The details are best left to "Locke" itself. It's enough to say he's decided that he must rise to meet an unexpected moral challenge, even if it means putting his marriage and career at risk.
This sounds heavy, and at times it is - you feel the weight of Locke's sagging world on his shoulders - but "Locke" is also frequently, intensely funny. Locke means (even if dismissed) to make sure that the project goes as planned, coaching a terrified (and increasingly inebriated) second-in-command through the prep process.
We get to know a lot about Locke in 80 minutes, and we get to like him, despite his acknowledged mistakes - perhaps because Hardy gives us a portrait of a fellow so agreeably out of step with modern times, given as they are to hysteria, selfishness and evasion of responsibility. Locke's humility, his calm and most of all his accountability give us one of the most quietly thrilling things we'll see in this season of blockbusters.