Algorithms are the invisible engines that drive every scroll, swipe or click. And, in the last few years, it's become clear that they can devastate young lives. But Ava discovers they might also be capable of saving them. 

She speaks with two teens with radically different stories. When 12-year-old CeCe Neltner went online to find workout tips, her social media feeds devolved into a torrent of eating disorder content. Today, she says she's lucky to be alive. Meanwhile, thousands of miles away, Keira MacDuff was battling a mysterious chronic illness that doctors dismissed as teenage drama – until TikTok's algorithm led her to a life-changing diagnosis.

Did TikTok save Keira's life?