Budapest's Underworld Orifice – The Piaf Club

4.15am. Touching the bell announces our arrival, the solid door opens and we're ushered inside the dark entryway for a moment by a curt but welcoming chief madame; short, middle aged and seemingly in a rush. To the sound of a piano she gives us a swift once over from head to toe. Cleared, we're handed a drinks voucher from a waitress' plain bum bag in return for the thousand forint entrance fee.

This is the point at which Kincső and I enter the Piaf Club, Budapest's greatest nightlife mystery, and a room dimly lit by elegant tasselled lampshades flanked by tiny bulbs swollen in bright red. Nestled on Nagymező street, just along from Budapest's ironic Moulin Rouge, Piaf's reputation for being odd doesn't disappoint. Yet seeing for myself, beyond the stories I've heard about this peculiar hive, it's odd in a surprisingly comfortable way; like using bathroom air freshener in lieu of deodorant.

In the flesh it's a small venue, with a curious mood that slides radically between the upstairs and downstairs. Upstairs the walls are coated with international newspapers, softened by generous draperies saturated the rich berry red of coughed-up blood gone dry. The slightly muted music oozes from the live piano like ancient phlegm over a relaxed clientele feasting on sips of strong coffee and cocktails through the last hour of darkness, tapping their feet against bar stools, eyes darting over now and again to us writing at the table in the corner. The doorbell occasionally rings, causing the madame to make her way slowly over, well-armed with a waist of cash. It's the relaxed yet intuitive form of screening employed by the female Piaf gatekeepers that maintains the uncrowded upper ambiance. Consistently they let in limited numbers at a time, before carefully motioning the new heads directly into the pit downstairs.

Adherents of Piaf brim with late night behaviour that's worlds away from their vomiting counterparts rampaging through the ruin pubs before limping back to hostels in a ubiquitous 3am blur. Esoteric dens of this calibre switch one's focus into an all-encompassing sensation – one that no doubt keeps its regulars, mainly unaccompanied men with an animated smattering of couples and wine-drinking foursomes, coming back to lick up ever more of this zesty insouciance. Charged, floaty music causes the brain to wander towards girls' faces turned in the shadows, seducing the room with glamorous hypnotic eyes, leaking with allure.

The enthusiastic pianist's heartfelt songs flood the space with a suitably heavy Hungarian atmosphere – a special aligned energy that I haven't found anywhere else in the capital. For Kincső, a man at the dark middle table epitomises it. He's melancholic beneath long brown hair and, seated opposite the pianist with a shisha pipe fixed to his neck, discerningly requests his old favourites – capable only of enjoying the slow, sad songs, since when the more impulsive arrangements peal out he abandons the entreaty and starts to use his phone. “What would I be worth without music....,” chants our entertainer in mellowed Magyar, before moving into a rendition of 'Strangers in the night'  that attracts a reverent sing-along. Then the piano man takes a sudden breather, and on blasts Charles and Eddies' 'Would I Lie To You'  from the speakers like a happy bullet through the room, at which a girl next to me stands out of her low lounge chair to gyrate from side to side for the rest of her table. A tray simultaneously arrives and we're served with pairs of miniature shots of strong piña colada. At such a pure moment this nightspot simply can't fail to make me smile.

The dried red room is a pseudo-family of unsuspecting people reclining on the sofas as sunlight rises covertly beyond the walls; a family of eyes contentedly sealed while still absorbing the Hungarian serenade – this time the sad end of a love story about a dropped cigarette that was still burning, and a man who feels the same.... dropped, while he was still burning. By now some customers are in a deep sleep across the furniture, not from drunkenness, you understand, rather in the manner of positive surrender to the long padded chairs, undisturbed by the barmaids in a state of unsullied, drifting intemperance. Lulled and carefree, the candlelight flickering near their faces outlasts them, while the rest of us watching on are nothing less than soft-eyed as more people arrive.

On the club's Facebook page, a customer from last year says of it that 'you enter another dimension and time stops.' Indeed, the thick red velvet blackout curtains block the time right out. But heading below ground you'll realise that Piaf also offers one big contrast within the same venue – snoozy opulence upstairs gives way to a horde of black brick depravity downstairs post-6am, when hands lift and expressions fall as the hot basement music grows heavier and darker. After descending the narrow stairs we elbow a path to a table through the strong muscles and shaved heads – through the nine parts men peppered with one part miniskirts and high boots. Transcending a simple party atmosphere, the packed Piaf cellar plops us deep into Budapest's underworld of unpredictables, indecipherables and side-grinners; thin-lipped interlopers, thirty-something intransigents, and bolt-on-type meddlers. Louder dance beats and stolid bar-leaning reign as twisting lights flash across their cheeks. Surveying it in full from the alcove, this basement is ideal territory for a discreet early meeting of henchmen and boondogglers.

Eventually we exit into full daylight and an immediate scenery of conked-out casualties lolling on the blistered pavement – revellers dozing against Piaf's facade – those who got here successfully this Saturday morning but couldn't make it past the screening. Stepping nimbly across their feet, amid the celebratory rush of broken glass and vulture taxis, I realise one thing... The sure conclusion is that the Piaf Club has evolved a magnificently slippery vertical spectrum of self-preservation for Budapest's nighthawks – mood-rich tranquility bound with jostling adhesive to a seething, jagged edge. You may even find yourself passing there one weekend at 4 or 5am. Our advice is ring once, adopt a rational expression, suck in a breath, and step in.