Dismayingly, Birthday Girl takes a huge wad of potential and blows it on trite delivery and implausible twists. The gist is that a lonely john named John (Ben Chaplin) works as a dull bank clerk and lives in a dull English suburb with a house full of annoying red ants apparently shipped in from Atlanta. Given this dire scenario, he scopes the Internet for a suitably exotic Russian squeeze, foregoing some horrific caricatures to land upon sexy Nadia (Kidman), who happily turns herself over to his custody. She's lovely, she likes him, and she wants to play house, but John is put off by the fact that she smokes -- the British leading the world in anti-smoking crusades and all -- plus the fact she doesn't speak English, so she hardly utters a word. Considering he's a total perv with a cabinet full of B&D porn, the problem is?
Given his puzzling dissatisfaction, John tries in vain to return the merchandise, but Nadia convinces him that she's a keeper. The two quickly bond via bondage, tutored by instructional manuals with titles such as Hog-Tied Bitches, and soon the relationship looks like a go. As Butterworth and his brother and co-screenwriter Tom know, however, this is the ideal time for a plot point. They provide this "surprise" on Nadia's birthday, when her alleged cousins Yuri (Mathieu Kassovitz) and Alexei (Vincent Cassel) arrive at John's house for a stay of unknown duration. Mayhem ensues.
It's truly unfortunate that Birthday Girl shoots itself in the foot, because there are plenty of functional elements on hand. Although Chaplin might serve us better as an actual bank clerk than an actor, he passes here as a Pollyanna with much to learn about life outside his hermetically sealed world. His increasing sympathy for Nadia makes no sense whatsoever, but their emerging chemistry is adequate to sustain curiosity, even when he learns he's just one of the Russian team's long list of scams.
The movie's real drag comes with Cassel and Kassovitz, which is odd, since they're both currently wowing audiences in Brotherhood of the Wolf and Amélie, respectively. Even though they play the Russian gypsy shtick endearingly enough at first -- their performances become so chummy, so cutesy, that the threat they soon pose to John's existence arrives colder than yesterday's borscht. Yes, with Nadia's help, they con John into robbing his own bank, and, yes, they leave him tied up on a toilet, but ultimately they're so smugly self-aware that Butterworth's movie falls apart.
Kidman, on the other hand, works hard for the money. Who knows what dosage she was slipped to persuade her to do this project, but she punches the clock with aplomb. Barring a few slips into Boris-and-Natasha dialect ("You spleet my fucking leep!"), she's the movie's truest element.
A shame, then, that the rest of this endeavor is such a mess, from its clangingly false emotional manipulation to the silliest "suspense" music ever composed on a kazoo. Butterworth is full of good intentions, but we know where those lead, and Kidman's presence, though pleasant, is merely bait for the box office. Ironically, like the Molotov cocktail it aspires to be, Birthday Girl is simply a bomb.