A small group of protesters marches towards Pakistan's parliament, pushing past nervous police officers.
Hundreds of Pakistanis have disappeared since 2001
They are carrying banners that say "Lost Souls" and "End Enforced Disappearances".
These are the families of the disappeared.
They are convinced their sons and husbands have been illegally abducted by the secretive intelligence agencies, and they are finally speaking out.
Human rights groups say hundreds have gone missing in this way.
Amina Janjua has become a veteran campaigner in the past 16 months.
Her husband Masood was picked up with scores of others after the London bombings in July 2005.
He was a Muslim preacher and social worker, but had no record of militant activity.
Unofficially, Amina has been told the security agencies have Masood, but she cannot confirm his location or get access to him.
For her, not knowing his fate is worse than knowing he is dead.
"If he was dead, I could cry my heart out," she says, wiping away tears.
"I could bury him, I could see him, I could compromise in the end. But when he is disappeared, I cannot compromise, I cannot forget him ever, I cannot stop being desperate."
People began disappearing in 2001 with the onset of the so-called war on terror.
The human rights group Amnesty International says Pakistan's security agencies, particularly the powerful ISI, often picked up suspects with little or no evidence, and sold them to the Americans for bounty.
The American embassy in Pakistan had no immediate response to Amnesty's charges.
Alleged suspects were 'sold' to the US, campaigners say
But Badr Uz Zaman says that is what happened to him.
He and his brother spent three years in Guantanamo Bay, then published a book about their experiences.
Shortly afterwards, Badr's brother was rearrested.
"In our book we criticised the ISI about its misdeeds, about selling people to America," he says.
Wary of being followed he is speaking from an anonymous hotel room.
"They didn't like being criticised, so they arrested my brother, and if I'd been there they would have arrested me too."
It is not just alleged terror suspects who are disappearing.
Domestic critics of the regime have also been taken, such as writers and nationalists, especially from the troubled province of Balochistan.
There are three or four new cases every week, say human rights organisations.
The government denies all knowledge.
"Wherever a person has been arrested, due judicial process has been adhered to," insists Interior Minister Aftab Sherpao.
When pressed for an answer about the disappeared he responds:
"Let's see where these people are, whether they're in the country, whether they've gone out somewhere. I don't want to divulge more because the Supreme Court is seized of this problem."
In fact, under orders from the Supreme Court, the government was forced to trace several missing men.
A few have now been released from army camps.
One told Amina he had heard her husband was being held in a military fort.
Pakistan's courts have found and freed a few prisoners
For human rights activist Khalid Khawaja the whereabouts of the disappeared is no longer a mystery.
"Now it is very clear that the people are with the army," he says, joining the families of the disappeared in their vigil outside parliament.
"So the army chief should be asked, where are the rest of the people? And all these torture camps should be closed, they're all illegal."
That will not happen, says another seasoned activist, Asma Jahangir, because the policy of enforced disappearances is sanctioned by the international community.
"After 9/11, the [Pakistani] government feels it can do this with impunity," she says.
"Because the Western governments are so keen to see a dictator in Pakistan who they can manoeuvre, there is no voice outside of Pakistan that is even condemning this or showing concern about it."
Still, there is growing determination to find the missing.
Court orders and demonstrations have succeeded in freeing a few of the disappeared.
But it is a tough battle, appealing to authorities which are formally committed to upholding human rights, but in practice seem to deny them.