Like a lot of lonely teenagers, Sarah found refuge on social media. In her lowest moments, she'd reach for her phone, connecting with strangers on Snapchat and Wizz – an app that's been called "Tinder for kids." But those digital friendships quickly became something more sinister. A torrent of older male users solicited her, and then, when she spurned their advances, blackmailed her.

For years, Sarah's life was in turmoil. And then she met a woman named Carol Todd, who took her under her wing. Carol understood what Sarah was going through, because the same thing had happened to her daughter, Amanda Todd, more than a decade earlier.

Now, Carol and Sarah are demanding change. What will it take to keep young women safe on the internet?