A warm, charming and bittersweet family drama, Piku turns the genre completely on its head.
The result is a magnificently original film that delivers a memorably unique movie experience.
Coming from the man who crafted Vicky Donor, a quaint drama around the adventures of a sperm donor, and got away with it, this comedy about constipation is par for the course.
What is truly surprising, and impressive, is that director Shoojit Sircar puts just enough spin on this wild whimsy to keep it whirling engagingly over its running time of two hours and a bit.
He is aided, of course, by a remarkable cast of actors who plunge headlong, and with full conviction, into the film.
Piku gives the go-by to the usual trappings of Hindi cinema and offers a fresh and deliciously quirky take on a deeply layered father-daughter relationship that borders on the dysfunctional.
Piku is the story of a cranky old Bengali widower Bhaskor Banerji (Amitabh Bachchan) who subjugates his paternal instincts to the health, or the lack of it, of his alimentary canal.
The more trouble that the crotchety gentleman has clearing his bowels, the more difficult he becomes for everyone around him, including a harried maid who he summarily accuses of kleptomania.
Mr. Banerji has a formidable counterpoint is an equally strong-willed daughter, Piku (Deepika Padukone), a busy architect who, despite the challenges that her dad poses every waking hour, takes the man's frequent mood swings in her stride.
Caught between the two is a cab service owner Rana Chaudhary (Irrfan Khan) who, as the baffled outsider in the course of a road trip that threatens to run off the rails, gives both father and daughter perspectives that promise to deliver them from the stalemate they are trapped in.
On the face of it, there isn't much scope for overt conventional drama in this narrative construct in which most conversations veer around to the old man's daily potty trouble.
But the film is packed with humour, poignancy and occasional dashes of bathos, which ensure that all the shit-talk does not stink.
The two central characters of Piku are the kind of figures that one does not encounter all that often in Hindi cinema.
The dad is an unabashedly selfish man. He does not want his daughter to get married because he dreads the thought of being left alone.
At the same time, he is a father who has no qualms about declaring that Piku "is not a virgin" and "is financially and sexually independent".
This, too, stems from self-interest: he uses his daughter's emancipated state to ward off potential suitors.
But Mr. Banerji also genuinely believes that it is "low IQ" of a woman to get married and devote the rest of her life looking after her husband and his home.
That is something that his own wife, a former teacher at Kolkata's la Martiniere School, had done. He does not want Piku to end up like her mother.
Not that the latter needs any prodding to keep thoughts of marriage at bay. Piku is fiercely independent and the men in her life, including her business partner, Syed Afroze (Jisshu Sengupta), are mere adjuncts.
The possibility of Piku and Rana developing an emotional bond with each other on a Delhi-Kolkata road trip remains just that - a possibility that stops well short of culmination.
Piku is not a romantic comedy although it has an entire strand that could have yielded a full-blown love story. That it does not only adds to its richness.
The drama in Piku is subtle and low-key. Not much of it bubbles forth to the surface.
It courses gently through innocuous scenes of domestic discord, alternating between the absurd and the emotionally enriching.
The drama is inherent in the little moments of disagreement and the sudden, rare flashes of consonance between the two central characters, and between the duo and the extended family.
The insightful writing (screenplay and dialogues: Juhi Chaturvedi) and Sircar's deft directorial touches fill every frame and every scene with delicious irony.
Piku isn't only about a man and his toilet travails. It is also about ageing, filial responsibility and nostalgia for what is gone forever.
Yes, Piku is also about the inexorable passage of time, which impacts everything - individuals, families, cities, cultures and belief systems.
Amitabh Bachchan, whose performance is otherwise effortless, tends to overdo the Bengali diction bit. What is worse, he does not get it right all the time.
That apart, there are passages in the film where Bachchan's presence works against the understated tone of the film.
It is Deepika Padukone who holds Piku together with a restrained star turn. She is believable all the way.
A characteristically confident Irrfan is, as always, pitch perfect.
Bengali singer-songwriter-composer Anupam Roy's musical score (his first for a Hindi film) is outstanding, enhancing the film's delicate emotional texture.
Piku is an absolute must watch.