TWO young Australian couples seem to be having a terrific fortnight's holiday in southern Cambodia enjoying the beachside bars, clubbing and dancing in the evenings.

Alice (Felicity Price), who is pregnant and expecting her third child, is with boat builder husband Dave and her younger sister Steph.

Steph (Teresa Palmer) has a new boyfriend Jeremy (Antony Starr), the person who has arranged a great holiday deal for the four of them.

But the idyllic beach and bar scenes soon switch to a blood-stained (and substance-affected), shirtless Dave (Joel Edgerton) staggering home at dawn.

Fast forward to concerned-looking Alice and Dave disembarking at Sydney from their Asian flight. They've come home to their two, young children.

But Steph is still in Cambodia, waiting to hear from Jeremy who has gone missing. Police from the two countries become involved and they widen their search for the missing man.

A lot of the film is set and shot in Sydney, with flashbacks to Cambodia, as the relationship between Alice and Dave teeters and conversations falter.

And Steph, so used to others sorting out her problems, becomes more and more hysterical. No one can trace, let alone track down, absent Jeremy.