Trouble arises when Amy learns Sheldon has applied for a one-way mission to colonize Mars. Also, a trip to the pet store ends in a fight for Sheldon and Amy, Leonard surprises Penny with a very "adult" purchase, and, Raj is caught snooping in Emily's apartment.

When Leonard and Sheldon are invited to speak at UC Berkeley, they take a detour to try to meet an idol. Also, when Bernadette and Howard battle over the fate of his Dr. Who TARDIS, Raj and Amy offer to settle the dispute with a game of ping pong.