Well, it could be that the lost girls were part of a scientific experiment gone wrong. They were in a facility where some sort of accident occurred. Maybe there was a power outage and all the security systems failed. The girls managed to escape but got lost in the complex maze - like corridors of the facility. Now they are on the run, trying to figure out what happened and how to get back to normal life while avoiding the people who are trying to recapture them for the experiment.
Another element might be a quest. The lost girls could be on a search for something important, like a missing family heirloom, and during their journey, they got lost. They keep looking for the item while also trying to find their way back to where they belong.
In addition to the main lost girls, there could be side characters such as wise old men or women who offer advice to the rescuers or the lost girls themselves. There might also be animals in the story. If it's set in a forest, for example, friendly animals could help the girls, or dangerous animals could add to the challenges they face.
It could be about girls who are lost, perhaps physically lost in a place like a forest or a big city. Maybe they are lost in a more metaphorical sense, like lost in life, not knowing their purpose or direction.