Star Trek: The Next Generation Season 7 Episode 25

Stardate: 47988.0 – Shortly after Picard is diagnosed with a long-term, potentially debilitating brain disorder, he starts experiencing bizarre shifts into three main time periods: 25 years into the future, a few days before the Enterprise-D is sent on its mission to Farpoint station, and the present. Picard realizes that Q is behind these shifts through time. Q finally reveals himself that humanity is still on trial, and that Picard must stop an event in the future that will halt the formation of life on Earth four billion years ago.