Complete story — includes the ending
Sarah's excessive use of the defective Intersect has erased parts of her memory, allowing Quinn to turn her against Chuck. She returns to Chuck and Casey in time to hear Chuck declare that the Intersect must be destroyed. By the time Sarah goes rogue and strands the team inside Government building, Chuck has caught on, and has secretly switched glasses. He and Casey now labor to restore Sarah's memories of Chuck, with a trip to their dream house, and backup of Sarah's video log.
Sources and content license
Source and revision history · Adapted from Wikipedia contributors, Chuck season 5. HTML formatting and reference markers removed. · Content license