Code Lyoko (Seasons 1–4)

Code Lyoko (2003) is a French animated series you can watch online on iFILM, where four teenagers shuttle between an ordinary boarding school and the virtual world of Lyoko to shut down a rogue artificial intelligence.

Yumi, Ulrich, Odd and computer whiz Jeremy stumble onto a supercomputer in the cellar of an abandoned factory, and inside it a girl named Aelita, trapped in digital reality. Freeing her means fighting XANA, a sentient program that uses Lyoko's towers to strike the real world — possessing machines, sending monsters, wiping memories. Each crisis, the kids get "virtualized," battle in Lyoko as their avatars, then return and pretend to be regular students. The animation runs on two tracks: hand-drawn scenes for the human world, 3D graphics for the digital one.

What carries the show is the double life and the cost of a secret no one else can know, not the action itself. Four seasons, a story that actually finishes, and a theme tune a whole generation grew up on. It suits viewers who want teen sci-fi with a real ongoing arc. Stream every season of Code Lyoko online on iFILM.