The episode 12 of "The Big Bang Theory," "The Hesitation Ramification," ended on a sombre note, as Leonard did not say yes to Penny's marriage proposal. In an inebriated state, Penny went down on her knee and proposed to Leonard.
Leonard hesitated and the offer was off the table, which made Sheldon question Leonard if the relationship between him and Penny is over. Leonard was not sure about that. In episode 13, "The Occupation Recalibration," Penny is likely to tell Leonard that he did the right thing by turning her marriage proposal down.
Spoilers of the upcoming episode suggest that Penny quits her job at the Cheesecake Factory to seriously pursue her aspiration to become an actress. Leonard expresses his support to that but when Penny resigns for real, he might hit the panic button.
Also, it looks like in the upcoming episode Sheldon will be jobless due to forced vacation imposed on him. Penny takes him along with her on her job hunt. Sheldon might want to know from Leonard what is the status of his and Penny's relationship, as he is very much part of the relationship. It seems Leonard and Sheldon had discussed about Penny, Leonard and Sheldon are living together.
At Caltech, Amy discovers that a geologist likes her. She is likely to find it hard to tell him that they are not going on a date after she accepts his invitation for a geology related event. Spoilers suggest that Raj and Howard will come to the rescue and will make it look like Amy is a lesbian. The spoilers reveal that the geologist is likely to attend the event with Howard and Raj.
Official Synopsis of "The Big Bang Theory' Episode 13, "The Occupation Recalibration": "Sheldon tries to relax after he is forced to take a vacation. Meanwhile, Leonard struggles to be supportive of Penny after she quits her job, and Bernadette seeks Stuart's help in replacing one of Howard's comic books."