Within a few days, French police have arrested three 15-year-old boys and a group of young women suspected of plotting jihadist attacks, prompting fears of a new type of attacker.
At the centre of the plots and probably more besides is, investigators believe, the shady figure of a 29-year-old French killer called Rashid Kassim. And he is reaching his prey through their mobile phones.
He has appeared in brutal propaganda videos from the heartland of the Islamic State (IS) group in Iraq or Syria and is thought to have had contact via social media with several of the young suspects.
But who is Rashid Kassim and how are the plots co-ordinated?
An amateur rapper and youth leader from Roanne, north-east of France's second city Lyon, Rashid Kassim is thought to have been radicalised either over the internet or on a trip to Algeria in 2011. Two songs were entitled "I'm a terrorist" and "Rap attack".
He fell out with his local Muslim community and left France with his wife and three children for Egypt the following year.
Little was known of him until he appeared in a brutal IS propaganda video after the Bastille Day lorry attack on Nice in July. In the video, he murders two Syrian prisoners and threatens similar attacks on the streets of France by French citizens.
Also known as Ibn Qassim, his focus is recruiting young French would-be jihadists, And he is said to use social media and chat groups, particularly Telegram. He urges his 300 followers to carry out what prosecutors have termed "terrorisme de proximite" (local terrorism).
Rashid Kassim and France's male jihadists
Little has been said by French authorities to incriminate him directly but he has been linked to a dozen plots and attacks, including the IS-linked murder of a police couple at their house at Magnanville east of Paris on 14 June.
The killer, 26-year-old Larossi Abballa, was "part of (Kassim's) Telegram group and Kassim had a real influence in this case," a police source told AFP news agency. Abballa streamed a lengthy rant on Facebook Live before police moved in to rescue the couple's son and shot the jihadist dead.
Rashid Kassim also played a key role in influencing and instructing the two French youths who murdered an 86-year-old priest in his Rouen church on 26 July, according to L'Express website.
In an audio message a week after Fr Jacques Hamel's murder at Saint-Etienne-du-Rouvray, a man believed to be Kassim praised the two attackers, Abdel Malik Petitjean and Adel Kermiche. Both young men, aged 19, had tried and failed to travel to Syria.
Again it was the social media app Telegram that enabled Kermiche and Petitjean to keep in touch with their IS masters and the 200 or so other subscribers to their encrypted channel.
Investigators believe it was Rashid Kassim who brought the killers together. Kermiche was local to Rouen but his accomplice came from the south-east of France.
Children lured to jihad
By early August came the first indication that Rashid Kassim was targeting women and children to carry out attacks.
His name has been linked a girl of 16 arrested at Melun, south of Paris, on 4 August and to another teenager in Clermont-Ferrand days later. The 16-year-old had gone on Telegram to announce her plan to launch an attack.
And within the space of a week, three boys aged 15 were arrested in separate operations in the Paris area, all linked to Kassim:
- On 8 September, a boy was detained in an upmarket area west of Paris and later accused of criminal terrorist association. Reports said he had been in touch with Kassim
- On 10 September, a boy of 15 was arrested in Paris on suspicion of planning a knife attack in a public place. Investigators said he had been under surveillance since April
- Then, on 14 September, a boy reportedly of Egyptian origin was arrested in Paris. He had turned 15 only days before, was in touch with Kassim on the Telegram app and had allegedly put himself forward for a terrorist attack
'Women taking action'
Another plot in Paris this month involved several women and was, in the words of Paris prosecutor Francois Molins, "remote-controlled" from Syria. Unconfirmed reports said Rashid Kassim was the inspiration.
In the early hours of 4 September, a car packed with gas canisters and jerry-cans of diesel was abandoned by female jihadists in a street near Notre Dame Cathedral in Paris.
It failed to go off because a cigarette left behind in the car went out.
Three women appeared in court on Monday, 19-year-old Ines Madani, Sarah Hervouet, 23, and Amel Sakaou who is 39. A fourth woman, Ornella Gilligman, has also been charged.
Sarah Hervouet had been in a relationship first with Larrossi Abballa, the Magnanville killer, then Adel Kermiche, the Rouen cathedral attacker.
Rashid Kassim went on Telegram to praise the women for launching attacks, according to Le Monde, asking "where are the brothers?"
"You have to understand, if women are taking action it's clearly because too few men are acting."