The guys are on a trip to San Francisco for a convention and end up taking the train because of Sheldon.  While on the train, the boys spot the star of Sarah Connor Chronicles, Summer Glau playing herself.  Leonard, Wolowitz and Raj each take a shot at hitting on her.  Raj, through the help of beer, is actually doing quite well with Summer until Wolowitz shows him it was non-alcoholic beers and it was simply a placebo effect.  Raj instantly stops talking and gives Wolowitz his shot. After being super creepy, Summer tells him there's no scenario in which he's getting her number and it's Leonard's turn.  As Leonard steps up and beings to talk to her, they arrive at her spot in Santa Barbara and she leaves.

Sheldon, meanwhile, was much more interested in his flash drive he left behind.  The drive contained his paper he wanted to show Dr. Smoot (a famous physicist, look it up).  Sheldon wants them to get off the train, but Leonard convinces him to call Penny.  Although it kills him, Sheldon tells Penny to enter his room and where to find it.  She gets him the paper and at the end of the episode Sheldon hands the paper to Dr. Smoot and makes such an ass out of himself Smoot's hilarious response is, "are you on crack?"