The guys run into Summer Glau on a train. The rest of the summary is not needed because the fact that friggin' Summer Glau is in the episode should be enough to win. It is.
This episode doesn't have the good writing it has usual. I would rate it 6/10. Fortunately they had Summer Glau who is the only person who rates 14 on a scale of 10 so combined this episode scores a 10. They should thank Summer for gracing them with her presence. I think I'm gonna check out the Terminator show now.
Too bad Sheldon and Summer never got to speak to eachother.