They take their marriage vows in front of the Taj Mahal, promising to see each other through life and death... And then they go right back to doing what they like best: conning the junta of its easily gotten money.

Meet Bunty and Babli. They aren't your average running-around-trees-shooting-the-breeze kind of lovebirds. Bunty and Babli are special, and not just because they are played by the very special Abhishek Bachchan and Rani Mukherjee.

Shaad Ali, whose debut film "Saathiya" was about a working class marriage gone unpleasantly awry, here sinks his teeth into a finely written caper that moves our endearing couple with devilish dexterity through a series of corny-and-funny encounters with petty crime.

Some of these caper situations are decidedly unique to Hindi cinema. Come to think of it, Shaad Ali's narration sets out to achieve an impossible dream: it makes the dreams of two small-towners the fulcrum of narration, and makes these dreams both funny and sad, sometimes both at once.

The way Rakesh and Vimmi meet on a desultory railway station in a dusty town of Uttar Pradesh seems almost like a parody of Mani Ratnam's "Dil Se" where Shah Rukh Khan spotted the forlorn figure of Manisha Koirala in a remote corner.

Shaad Ali loves trains and other modes of communication for the working class. Dammit, he loves the working class! Not too many filmmakers today dare to follow small town dreams. Like "Saathiya" his romance is rooted to a real milieu. But there's a difference in "Bunty Aur Babli". Here the couple's escapades border on the bizarre.

The way Rakesh invents doubles for the two-some is a tongue-in-cheek swipe at armchair psychology. All the criminal activities that the pair indulges in is the handiwork of the couple's doppelgangers, alias "Bunty Aur Babli".

The comfort zone that Abhishek and Rani create for their characters' comic romp is mystical and yet earthy.

What was the need to suddenly brake on the burlesque mood, and put the pair in a lengthy erotic song?

At such times, Shaad Ali's considerable pluck plummets. You wait for him and the film to survive the compromises that creep into the second-half. But the joie de vivre and kinetic energy of the pre-intermission phase never quite returns.

Oh well, enjoy the blizzard and the blast of ruggedly visualised episodes while they last, as the two dreams steamroller their way through a stupendous rush of celluloid adrenaline.

It's regrettable that the film's deeper darker beyond-caper thrusts get drowned in the din of dusty retribution in the second half. As their blast from the past catches up with "Bunty Aur Babli" in the form of a scowling sneering cynical cop (Amitabh Bachchan) the caper kingdom of the innocuously anti-social protagonists falls apart.

It's the fun fiesta of petty crime that irrigates the strange and satirical world of Rakesh and Vimmy, also known as "Bunty and Babli". Abhik Mukhopadhyay's camera captures the dusty crusty rusty and thirsty milieu of north India in shrieking silhouettes.

In the opening song "Dhadak dhadak", we are introduced to the dreams and yearnings of the twosome with an infectious gusto. Indeed Rani Mukherjee and Abhishek Bachchan transform into the deviously self-gratifying heist-makers with a feisty passion. Their faces and body languages convey the eagerness of eagles waiting to take wing.

Rani's comic timing, specially in the sequence where, missing her parents after her runaway mirage, she wails like a baby is a delightful reminder of growing confidence as a performer who surrenders to the camera unconditionally. In the portions where she impersonates high society women, Rani seems to miraculously mimic Sharmila Tagore and Kareena Kapoor simultaneously.

Throughout the film we hear and see references to cinema of the past. For one conning interlude, Abhishek impersonates his father gravely dialogue delivery in "Agneepath". Songs from the Amitabh Bachchan films of the 1970s are played like parodies on the soundtrack.

Abhishek Bachchan's power to hold the camera with his steady and deep gaze deepens the impact of the caper immeasurably. While Rani pulls out all stops, Abhishek gives a reined-in, often hilarious performance in a series of disguises that he flaunts without an exaggerated swagger. His disguise as a 'bhaiyya' tout from Uttar Pradesh hawking the Taj Mahal to a dumb American millionaire (complete with a Mayawati look-alike chief minister) is priceless.

As for the senior Bachchan, in how many ways has he played the cop before? And yet his surly boorish lawman's role here delights you, specially when he gets on the dance floor with his son and Aishwarya Rai for a rabble-rousing qawwalli that could possibly rank as the grandfather of item songs.

Positioned invitingly in the second-half, this item song seems to dictate a large chunk of the footage, some of it unnecessary.

You often feel Shaad Ali could have made better use of the invaluable father-son combination. The dialogues and the situations created between the two Bachchans leave you thirsting for more. The dialogues, though incisive and topical, lack the bite and impact that the narrative demanded.

Some of the shared screen space between the two Bachchans is uneasily gimmicky. For a film about protagonists who break rules and a film that breaks many rules, it's embarrassing to hear the senior Bachchan say: "You've begun to seem like my own child" to Abhishek. It's completely out of character and context.

Maybe it's the parched wasteland where the comic drama unfolds...Throughout we see Bunty and Babli as wickedly naughty wannabes trapped in a bubble that you know won't burst on them.

In fact the film's moral ambiguity is intriguing.

Does Shaad Ali approve of small town people harbouring big time dreams? On the verge of retribution, Bunty and Babli with their new-born child are virtually pulled out of the gallows by the surly cop and put back into their original milieus, and then again "rescued" out of their humdrum existence to "con happily ever after."