A man named Ahmad Rashidi, who lives in England, was asked by a British family to help free their teenage daughters who fled to Syria to marry ISIS fighters. Ahmad agreed to help, but was captured by ISIS and held as a prisoner for about a month until he eventually was released.
During his capture Ahmad was beaten rather severely, but eventually managed to convince ISIS that he wanted to join them. The first year medical student claimed to be a doctor who wanted to help their cause. Eventually this allowed him to gain their trust and bought him his freedom on condition that he stay and fight with them.
Ahmad was able to escape back to Europe but is now a wanted man by ISIS.
While with ISIS, Ahmad learned of their desire to become greater than Al-Qaeda. He says of ISIS:
They want to be more better than Al Qaeda, Islamic State. This is why they need to do something more brutal than the World Trade Center…When the Islamic State attacks, they will be big. It’ll be very, very big.
Here’s the full interview: