A 16-year-old who lived in a household of terrorist propaganda, including pictures of beheadings, must be removed from her "deceitful parents", a judge has ruled.
The east London teenager, described as "intelligent, educated and ambitious", is "fully-radicalised" by Islamic State propaganda, the Family Division of the High Court heard.
Mr Justice Hayden said the girl, who cannot be named because of her age, has been left suffering psychological and emotional harm from her radicalisation akin to that seen in sex abuse cases.
She has already tried to travel to Syria to become a "jihadi bride", being removed from a Turkey-bound flight in December and made a ward of the court.
Her parents had then appeared to cooperate with police and social workers.
But when police searched the family home in June, they found "a plethora of electronic devices", including some belonging to her father, containing Islamic State material and showing that the parents had been deceiving the authorities.
Along with pictures of beheadings, there was material on bomb making and advice for jihadists on how to conceal their identity.
The judge said of the girl: "I can see no way in which her psychological, emotional and intellectual integrity can be protected by her remaining in this household.
"The farrago of sophisticated dishonesty of the parents makes this entirely unsustainable."
The judge described the girl as one of a number of "intelligent young girls - highly motivated academically" who had been "captured and seduced" into seeing life in Syria as a "jihadi bride...is a somewhat romantic and honourable path for them and their families".
He read out a list of terrorist-linked material found in the search, including devices belonging to the teenager which contained documents such as 44 Ways To Support Jihad and advice on how to avoid airport security.
She had had guidance for making weapons and bombs and had searched online for software to mask a computer's IP address and the response times of the Met Police armed response team.
The judge said her siblings had IS news reports of men getting ready for death, human "executions", beheadings, terrorist training and propaganda videos.
The children's parents had devices containing lectures encouraging attacks on non-Muslims, all discovered after the parents had expressed their thanks that their daughter had been prevented from reaching Turkey, the judge added.
Comparing the case with those involving sex abuse, the judge added: "The violation contemplated here is not of the body but it is of the mind.
"It is every bit as insidious - and I do not say that lightly - as it involves harm of a similar magnitude."