They are young, female, and in love - and they are the doomed followers of a man known as Russia's Osama bin Laden.
They are the "black widows" of Russia's extremist terrorist group and are selected for death almost from the moment they join up.
Lured by the promise of a key role in a coming Russian holy war led by a charismatic madman with bin Laden-style aims, the women - some still in their teens - enjoy a brief, passionate relationships with Russian men who are also terror recruits.
Then, after he blows himself up in a suicide bombing, the new widow prepares herself for her own fiery end.
Willing to become martyrs for their beliefs and their lost loved ones, they enter train stations, buses and airports strapped with explosives destined to cause death and havoc.
The cult of the black widow is striking fear in the hearts of Russian parents who are losing daughters and sons to the terror group which is bent on a suicide bombing jihad.
Following two lethal bomb blasts in the southern Russian city of Volgograd this week, fears the terrorist cult will threaten the safety of Australians and other athletes competing in the Winter Olympics next month have escalated.
The leader of the group is Doku Umarov, a 49-year-old former oil construction engineer turned Islamic war lord and now dubbed the country's Osama bin Laden.
The US government has placed a $5 million bounty on the head of the Chechen-born self-proclaimed emir of a new Muslim state he calls the Caucasus Emirate.
Umarov has made a direct threat against the February 7-23 Sochi Games, saying it was his holy duty to prevent them from taking place.
Authorities believe Umarov is operating his terrorist movement out of the strife-torn southern republic of Dagestan, which lies between the Caucasus mountains and the Caspian Sea.
Umarov has denounced the establishment of Sochi's Olympic village as a defilement of the "sacred ground" once occupied by Circassians, who were "ethnically cleansed" by Russia in the 19th century.
Although young terrorist recruits to Umarov's movement have come from all over Russia, at least one black widow, Naida Asiyalova, who blew herself up in a suicide bombing in Volgograd in October, is from Dagestan.
Known as Amaturahman, Asiyalova was in love with another suicide bomber before she "did her duty" to the jihad cause.
She was a close friend of the missing woman initially implicated in this week's Volgograd station bombing.
As the death toll rises from the Volgograd bombings, Russian investigators have linked the explosions.
Russian Investigative Committee spokesman, Vladimir Markin confirmed Sunday's Volgograd train station was the work of a suicide bomber, whose "signature closely matches" the following day's bomb on a trolleybus.
Police first identified 26-year-old black widow Oksana Aslanova.
Russian news source Life News published a picture of what it reported was her bloodied head lying amid a pile of debris with her long brown hair spread across the train station floor.
Aslanova, who has been on Russia's wanted list for two years, has reportedly been married to two Islamic militant leaders liquidated by Russian forces in the North Caucasus.
After investigators found further remains - a male finger with a pin from a grenade - among the debris at the crime scene, a new culprit emerged.
Pavel Pechyonkin, a medical school graduate, left Moscow to join Dagestani militants in 2011.
It is believed he became a disciple of Doku Umarov.
Oksana Aslanova is now thought to be still at large.
As Russian president Vladimir Putin ordered a further security crackdown, Sochi, which lies west of Dagestan on the Black sea coast, is being turned into a massive security fortress.
Umarov is said to excel in hostage-taking and suicide bombing, favouring buses, trains, rail stations and airports where he can kill and maim as many people as possible and cause maximum transport mayhem.
These are the bombings he is credited with and the black widows or young male recruits it is said have danced to his tune:
Dzhennet Abdurakhmanova was only 16 when she met and married Umalat Magomedov, a Dagestani Islamist rebel killed in 2009.
A classic, if very young example of the "black widow" cult which is a feature of the Russian Islamic terror campaign, Abdurakhmanova was part of a nationwide recruiting campaign by the Chechen rebel group.
Once lured in, the women are immediately treated as potential suicide bombers. They are not told this, rather they are treated the same way as male recruits and included in discussions about the right and wrong ways of Islamic faith.
Then the girl becomes a wife or mistress of the young war lord.
Abdurakhmanova's husband, Magomedov, aka Emir Al Bara, was the leader of the Shariat Jamaat organisation in Dagestan and an appointee of Doku Umarov.
After the husband's inevitable death - Magomedov was killed by Russian security forces on 31 December 2009 - the new widow may become the wife of another member of the armed underground.
From thereon, the black widow begins a new stage: preparing for suicide bombing.
Abdurakhmanova, whose real name was Janet Abdullaev, was one of two women earmarked by Umarov to carry out bombings during the morning rush hour at Moscow's Metro station on March 29, 2010.
At the time, an estimated 500,000 people were commuting through the Moscow metro system.
At least 40 people died and more than 90 were injured.
Russian officials called the incident "the deadliest and most sophisticated terrorist attack in the Russian capital in six years".
About 48 hours later, a double suicide bombing in the Dagestani town of Kizylar killed 12 people including nine policemen.
Four days on, another explosion derailed a freight train in Dagestan.
The second black widow turned suicide bomber responsible for the Moscow metro explosions was 28-year-old Maryam Sharipova.
Married to close Umarov associate, Magomedali Vagabov, killed in an operation in Dagestan along with four other militants in August 2010, Sharipova was identified after police released photographs of her remains in the bombing aftermath.
Sharipova's father recognised his daughter in photographs of her remains.
He told authorities Sharipova, who taught computer science at a local school, had gone missing the day before the attacks.
She had allegedly told her mother that she was going to visit a friend. The couple had not heard from her since.
Sharipova, who lived with her parents in the village of Balakhani in Dagestan, was never known to show extremist views or unusual behaviour, her father said.
Naida Asiyalova, whose jihadi name was "Amaturahman", was a 30-year-old Dagestani national
and alleged wife of Dmitry Sokolov, a militant in the regional capital of Makhachkala.
Neighbours from her village remembered an ordinary, westernised girl who was not religious, but who married a Turk, and "then something happened" and she "changed completely" and began attending the mosque and wearing a scarf.
Asiyalova and Sokolov met in the Moscow suburbs, where she recruited him to radical Islam.
They later left the capital to join rebel groups in Dagestan.
Sokolov was reported missing in July 2012 after he failed to return home from Arabic language courses that he attended at one of the capital's mosques.
Taking on the rebel name of Abdul Jabbar, he allegedly took part in the two 2010 Dagestan explosions.
Russian media reported Asiyalova had a serious disease which caused her jawbone to recede and required tranquillisers and painkillers.
A fundraiser was previously organised on social network VKontakte for her treatment. It stated that she had a disease which caused her jawbone to recede.
Asiyalova constantly changed her place of residence from Makhachkala to other Dagestani cities, where she met with the widows and wives of militants.
An ardent convert, she was popular and had access to money collected at Muslim gatherings aimed at preaching Islam.
On the morning of October 21 last year, she boarded a bus in Volgograd with explosives strapped to her body beneath her flowing veil.
At about 2.05pm. Moscow time, she detonated the bombs, killing six people and injuring 37 others, included a 20-month-old child.
Now one of the most wanted women in Russia, Oksana Aslanova is reportedly the black widow of two extremist warlords.
Born in 1987, she later moved to Dagestan, where she married Mansur Velibekov, a Chechen radical and member of a criminal ring wiped out in 2008.
Upon his death, Aslanova became a so-called "Sharia wife" of the gang's leader, Gasan Abdulayev.
Another report suggests that Aslanova was also married to a known terrorist, Israpil Validzhanov, who went under the nickname of Amir Hasan.
He was eliminated on March 18, 2011 near the Dagestani village of Tashkapur.
She has been missing since March 8, 2012 and it is now believed the "black widow" who outlived three husbands has undergone training as a suicide bomber.
Police now think one-time trainee doctor, Pavel Pechyonkin, self-detonated the bomb in Volgograd's railway station this week, killing 17 people.
Pechyonkin left Moscow in 2011 to join militants in Dagestan and subsequently posted a video on YouTube saying that he was following God's will and was working to earn a place in heaven.
His parents Nikolai and Fanaziya desperately tried to save their son.
Mr Pechyonkin said initially Pavel had changed for the better.
"He stopped arguing with me, did not drink, went to the mosque. I bought him Halal meat," he said.
Then following a visit to Moscow, he vanished.
The Pechyonkins heard he had gone "in the forest" with rebels and made an internet appeal for him to return, to which he replied: "It was sad to see your tears, very sad.
"I didn't even want to watch. I thought it would weaken me. I came here so Allah would be pleased with me, to earn my way to paradise."
They travelled to Dagestan, hoping to rescue him from the militants.
The Moscow Times quoted his mother saying, "imagine somebody were to kill your parents, how would that make you feel? Why are you turning children into orphans?"
Pechyonkin told his parents he had then decided he would not be swayed.