The filmmaking works in and of itself, but that Lakewood feels so emotionally in tune with its lead actress is a feat all on its own.

Directed with brisk efficiency by Philip Noyce, the mix of adrenaline-rush emotion, manipulative melodrama and moralising is surprisingly entertaining in the moment.

While Noyce and Watts try their best to ramp up tension, Sparling’s foundation proves too flimsy to comply.

Before things go south, there’s an effectively clammy escalation of panic as Watts leaps from call to call . . . But the script, from Chris Sparling . . . isn’t quite ingenious enough to find ways to involve her in the drama.

Watts’ commitment holds the movie together. She acts as if that phone were her flesh-and-blood partner. But it’s not. It’s a device impersonating something human. And so is Lakewood.