(explosion) (cheering) (explosion) (gunfire) (gunfire) (chanting) >> aboude: >> narrator: but now aboude'srother has gone missing. and his family fears he has been captured by islamic extremists. >> helen: >> abu ali: >> mohammed: >> aboude: ♪ >> go to pbs.org/frontline. (chanting) learn more about the spread of isis inside syria. explore our full archive of films from the warzone. (crying) read a series of stories from our partners at mcclatchy. and connect to the frontline community. sign up for our newsletter and follow us on facebook, twitter and pbs.org/frontline. >> narrator next time on frontline... >> i like... >> i like... >> i like... >> narrator: the power of like. >> companies know how to turn like into money. >> narrator: the kids who are liked... >> this is my first bite of a cool ranch dorito taco. >> narrator: and the advertising machine spinning likes into gold. >> your consumer is your marketer. >> this is the biggest transformation that we've had in our lifetime. >> narrator: inside "generation like." >> frontlineis made possible by contributions to your pbs station from