Women in short skirts and men with gelled hair bump and grind on a dance floor as a disc jockey pumps up the volume. The air is thick with illicit smoke and shots of hard liquor are being passed around. Couples cuddle and kiss in a lounge.
This is not Saturday night at a club in New York, London or Paris. It is the secret side of Pakistan, a Muslim nation often described in the West as a land of bearded, Islamic hardmen and repressed, veiled women.
Pakistan was created out of Muslim-majority areas in colonial India 65 years ago, and for decades portrayed itself as a progressive Islamic nation.
Starting in the 1980s, however, it has been drifting towards a more conservative interpretation of Islam that has reshaped the political landscape, fuelled militancy and cowed champions of tolerance into silence.
But the country remains home to a large wealthy and Westernised elite that, in private, lives very differently.
Every weekend, fashion designers, photographers, medical students and businessmen gather at dozens of parties in Islamabad, Karachi and Lahore to push social boundaries in discreet surroundings that would horrify, and enrage, advocates of the stricter brand of Islam.
"This is just epic," said Numair Shahzada, bobbing his head to the beat at a party in a farmhouse outside Islamabad as fitness instructors moonlighting as bouncers looked on. "The light and smoke show is phenomenal."
Young men and women mix freely, dancing, talking or drinking. Some curl up together in quiet areas.
Although alcohol is prohibited in the country, many have brought their own liquor. Whisky is carried in paper bags and vodka is disguised in water bottles arranged along the dance floor.
The party-goers form only a tiny minority of the country's 180 million people, but overall, Pakistan is not repressive. Women can drive, are enrolled in universities and have played prominent roles in politics. Unmarried men and women can interact without risking the wrath of religious police.
People from its most populous province, Punjab, are renowned for their exuberance.
But a conservative form of Islam is chipping away at the tolerance.
A few hours drive from Islamabad's party circuit, parts of remote tribal regions have fallen under the sway of hardline Taliban militants, who dream of toppling the government and creating a society where revellers would face flogging, or worse.
"Men and women who dance together are damned by God. Whenever we see such displays of vulgarity we will definitely make them a target," said a senior Taliban commander.
News reports have said a tribal council in a village near the Afghanistan border ordered four women killed earlier this year for clapping and singing as men danced at a wedding. The Supreme Court has ordered an investigation, but there have been no further details.
While the vast majority of Pakistanis abhor the Taliban's violence, there are many who share their belief that Islam should be Pakistan's guiding force. Religious parties, which do poorly at the polls but exert considerable sway over public debate, believe Islam should govern all spheres of life.
"It's so messed up," said Myra, a 23-year-old Pakistani who has dyed her hair reddish-brown.
"You see the servants and the drivers at the parties watching you and you wonder what kind of a person they think you are."
To avoid prying eyes, the kind of alcohol-fuelled blow-outs enjoyed by Myra and her friends are held in lonely farm-houses in the outskirts of Islamabad and other cities, or in affluent neighbourhoods behind high walls. Organisers charge on average a $60 entry fee, an amount most Pakistanis earn in a month.
Rafia, petite with long, black hair and wearing tight jeans and a low-cut black blouse, is a regular on the party scene.
She frowns on women who carry secret cell phones unmonitored by their parents and wear revealing outfits under conservative dress that come off before getting on the dance floor.
"You can either be God-fearing or you can party," she said, taking a drag on a marijuana joint at a recent rave.
"I don't pray regularly and I usually stick to my fast. But at the end of the day, I don't say I am a very religious person."
Not everyone agrees.
Bina, 40, an attractive fashion designer, showcases nude paintings and topless male models in shows. She also wears a silver pendant engraved with a verse from the Quran
"People think I am shameless but I am actually very religious," she said at her studio, peppering her sentences with "jaani", Urdu for darling, while chain smoking.
"My faith is very strong. But everything I do is between my God and me."
Conservatism began sweeping through Pakistan during the military dictatorship of General Mohammad Zia ul-Haq in the 1980s under a drive to Islamize the state.
Zia's policies are widely blamed for a creeping culture of intolerance that has further isolated liberals.
In an incident that traumatised the elite, the governor of Punjab province, Salman Taseer, was assassinated by his own bodyguard last year for opposing harsh anti-blasphemy laws.
The reaction was almost more shocking to liberals than the murder itself. Clerics organised huge rallies to praise the killer. Even lawyers, once at the vanguard of Pakistan's democracy movement, showered him with rose petals.
In the growing climate of fear, the space for liberal voices is shrinking.
Pakistani rapper Adil Omar, who attends weekend parties, pokes fun of the Taliban and rising conservatism in his songs. But he never goes too far.
"A lot of people seem to be torn and seem to have an identity crisis," said Omar, who wears the traditional flowing shirt and baggy trousers. His elaborate forearm tattoo featuring a semi-naked woman and a unicorn has drawn fire on his Facebook page from some fans who see it as an offence to Islam.
"I am careful not to give any opinions regarding religion on the record," he said, adding: "I don't want some crazy person chopping off my head."