The last time we saw a postman in our cinemas it was Kevin Costner grandstanding amid the post-apocalyptic debris: three self-aggrandising hours of beaten chest and waved flag. Needless to say it is not at all like Pål Sletaune's Junk Mail. Except to say that this Oslo occasionally looks pretty post-apocalyptic itself. Punching in at a smidgen over 80 minutes, Sletaune's template is more Aki Kaurismäki than Mad Max, its hero a peeping tom who dumps half his round daily in a railway tunnel. Kevin would not approve.

Roy (the excellent Robert Skjærstad, looking spookily like Tim Roth's even seedier brother) is the slacker postie besotted by the sad-eyed and deaf Line (Adriane Sæther) who works in a local dry cleaners. Accidentally acquiring her keys, he passes his empty days in her dismal, run-down flat. Until, that is, he falls asleep and finds himself having to foil a suicide attempt. She was involved, he discovers, in a robbery that left a security guard in a coma and her violent ex-boyfriend (Per Egil Aske) angry.

If there's a flaw in Sletaune's quietly arresting debut then it's the plot's over-reliance on Hitchcockian coincidence: all the parts slide very nicely together. Fortunately, though, Sletaune and co-writer Jonny Halberg are more than intent on larding their darkly humorous screenplay with a wealth Kaurismäki-like detail: Line's larder consists entirely of packets of Frosties; boyfriend Georg emerges from the shadows to menace Roy with the theme from Postman Pat; and, most memorably, there is the sort of grotesque karaoke evening that would give even David Lynch pause for thought. One might even read it (the loner Roy in his battered khaki jacket, his and Line's stilted coffee shop encounter) as a perverse homage to Scorsese's Taxi Driver.

Dark, damp and glum, the film's finale is suitably abrupt and ambiguous. Its director calls it, "a black comedy about love, money that no one wants, cold canned spaghetti, karaoke, involuntary good deeds, rutting and the joy of being comatose." It is. And sometimes that's enough.