Five years after escaping Aperture, Chell is tasked with Wheatley's desperate request to go back in time to stop him from ever becoming a robot. However, there are some things in the past that Chell was never prepared for.

Meteors, signals, apologies, and that tricky little thing called humanity- four years after the events of Portal II, Wheatley's been handed a second chance, but it's not going to be plain sailing…