Social media profiles on Snapchat and YouTube described Emma Dixon as a 10-year-old who loved swimming, dogs, horses, ponies and slime. Online, she chatted easily with other young boys and girls drawn to the platforms fast-paced, highly engaging content.

Packed with music, gaming advice and animation, YouTube has become a powerful magnet for young viewers, with billions of videos being watched daily. Pew Research Center found that 80% of parents with children under 12 said their child uses YouTube — more than half daily and about one-third log on multiple times a day — making it the internet’s top destination for kids, followed by TikTok, Snapchat and Instagram.

But in Emma’s case, something was terribly wrong.