If you've ever wondered what on earth is on-screen chemistry, here's your one-stop all-purpose encyclopaedia on celluloid magic.

Fasten your 'see'-it belts, as veteran filmmaker Rajkumar Santoshi sheds all his Lajja and pulls out all the stops to do a wacky, goofy, edgeless, weightless comedy of characters who walk in and walk out of frames leaving behind fumes of old fashioned funnies.

Ajab Prem Ki Ghazab Kahani is an airtight trapeze down that familiar romantic lane. The starting point seems to be Saawariya. A wacky, loud, opened-up, rimless and riotous interpretation of Ranbir Kapoor's character in Sanjay Leela Bhansali's opera on screen, Prem in Ajab Prem... adores the fresh scrubbed girl next door Jenny. But she loves someone else. No it's not Salman Khan, though in a tongue-in-cheek homage to tabloid realism Katrina meets her idol Salman who drawls to the roadside Romeo Ranbir, "You're behaving as if you're making my girlfriend or your own."

Touche.

As in Saawariya and his more recent films Bachna Ae Haseeno and Wake Up Sid, a major part of the narrative becomes a showcase for Ranbir Kapoor's skills as an all-purpose actor who can pull out any emotional response to the most sterile dramatic stimuli. In sequence after sequence, written to spotlight the young actor's virtuosity, Ranbir rises above the material given to him with glorious gusto.

Even while mouthing corny maudlin sappy dialogues about serving moong-dal ke pakaude to his beloved or plucking stars from the sky for her, Ranbir makes the trite seem just right.

His phenomenal talent gets radiant support from Katrina Kaif who gets better with every film. As the waif with a face so vulnerable and imploring you want to protect it from the harsh rays of evil sunlight, Katrina Kaif is at once wholesome and haughty, feisty and flirtatious. She's every man's dream-come-true, so why not Prem's?

Would Ajab Prem... have worked as such a swimmingly sleek showreel for the besotted-boy-meets-the-absentminded-waif's tale without the same lead actors? The answer, frighteningly enough, is an emphatic no.

The noticeably over-done comic situations include a cartel of goofy goons who pop up towards the end to join the party. In one laboured sequence of comicality Ranbir must wear Katrina's bodice and pretend he wears such clothes comfortably to avoid exposing Katrina's concealment in his home.

The above scene defines the sense of inner-wear weariness that Ranbir and Katrina effectually avoid and alchemize into a watchable potpourri of parodic passion.

This is a rare film that surmounts and jumps over all the hurdles of clichéd plotting and corny dialogues on the sheer strength of its protagonists' charm and grace. The film wears a bright bouncy sunny look. The location is an obviously papier-mache town filled with a benign bonhomie which doesn't go beyond the rituals of surface-level romanticism.

And yet, several individual sequences come alive to convey a sparkling potency. Check out those sequences where Ranbir and Katrina stammer under emotional stress both individually and separately.

The couple in Kaminey seems suspiciously rehearsed in comparison. Indeed, though the material provided to the lead reeks of second-hand emotions Ranbir and Katrina embrace those emotions and make them scrubbed.

Is there a better star-pair than Ranbir and Katrina in recent times? Maybe there is. But who cares. This one just makes you want to cuddle them.

Rating: ***