The French film 'Lew Cowboys' is about such a girl. She doesn't travel to Syria, neither does she engage in violence, but she disappears suddenly with her Muslim boyfriend, leaving her father, mother and brother behind in fear and despair.
Her father decides to devote his life to the search for his daughter. For several years, he tries to follow every trace that can lead him to his daughter Kelly. Het becomes so obsessed that he risks his job, his marriage and eventually his life in order to find his daughter. Later on, the same goes for Kelly's brother.
The desperate search leads father and son from one shady informer to another. They follow traces in France, Belgium and Pakistan. The authorities soon give up the quest for the disappeared teenager, but thanks to their tenacity and some luck, the father and brother have enough clues to continue the search.
The quest is filmed in a neutral style, not providing a moral judgment of the girl's behaviour, but concentrating instead on the father's despair and the brother's obsession. The story is spread out over several decades, with the terrorist attacks in New York, Madrid and London providing some indication of the time frame in which several scenes take place. The film's bottom line is a bleak one: when you spend your life searching for something, finding it in the end can be a bitter disappointment.