Sheldon calls Penny and convinces her to break into his apartment to find the drive. This leads to a comedic sequence where Penny has to navigate Sheldon's elaborate security measures, including a Japanese puzzle box . Key Highlights

In Season 2, Episode 17 of The Big Bang Theory , titled the gang boards a train to San Francisco for a physics symposium. Plot Overview

Sheldon insists on taking the train instead of flying, leading to a long journey where the guys discover that Summer Glau (from Terminator: The Sarah Connor Chronicles ) is a fellow passenger.