PlotIn the season seven finale, Leonard and Penny announce their engagement to their friends, Raj's relationship with Emily is taken to the next level, and Stuart's comic book store burns down. Unable to cope with all these changes, Sheldon decides to take a train sabbatical.
- Chasing a Butterfly: When Sheldon goes missing, Leonard tracks down his phone, a precaution he took ever since Sheldon wandered off chasing after a balloon at the swap meet.
- Insurance Fraud: Invoked. When the comic book shop burns down, everyone assumes that Stuart did it for the insurance money, including the insurance company, the person's mother and Howard.
- It's All About Me: Sheldon doesn't take kindly to the idea of Leonard moving in with Penny.Sheldon: You're putting your future bride's happiness above mine!
- Journey to Find Oneself: After all the changes in his life, Sheldon decides to ride the rails for a while to clear his head.
- Wham Episode: Overwhelmed by too many changes, Sheldon leaves on a train trip to sort himself out; the comic book store burns down and Stuart moves in with Howard to take care of Mrs. Wolowitz.