Sheldon is working in his office on a math equation. He here’s a strange high-pitched voice call his name. He looks out in the hallway, and the light blows out, he guesses someone is playing a Halloween joke on him. The lights come back on and Howard and Raj run out and try to get him to admit he was scared. He goes back in his office, turns around, screams and then faints at an alien standing behind him…Leonard in a mask.
At the comic book shop, the guys tease Sheldon about his freak-out. Stewart walks up to them and tells them a hot girl just walked in, and he approaches her, but can’t finish his sentence. She then approaches Leonard, and gives him her phone number and says her name is Alice.
Leonard and Sheldon get back to the apartment. Sheldon insists Leonard goes to get the mail, and plugs his ears when Leonard goes to open the box. Nothing happens so he goes to check the mailbox, which Leonard has now rigged with his own prank.
Alice and Leonard are looking at comics, and she shows him the comic book she’s working on, and then they start making out.
Sheldon goes to his office, and brings in a box with a snake inside that he then sticks into a drawer in Raj’s desk. Raj walks in and Sheldon tries to act like he ran out of staples. He ask Raj for some staples, Raj opens the drawer and is excited to see the snake and babies it before taking it to the biology lab.
Leonard goes to visit Penny, to get some advice about the fact that he kissed another girl while he is still in a relationship with Priya, but Penny isn’t much help to him.
Leonard goes to leave for a date with Alice, but then stops himself, because he says he’s having a moral crisis. He talks to Sheldon, and decides to go out.
Sheldon goes to Howard’s house to try to play a prank on him. He uses a hand buzzer on Howard, and he and Bernadette trick Sheldon into thinking he seriously injured Howard because he has a heart condition.
Leonard tells Alice he has a girlfriend, and she gets mad at him, and kicks him out.
Leonard video chats with Priya to tell her what he did, and then she admits she had slept with her ex-boyfriend. He hangs up with her and Sheldon pops out of the couch in Zombie make-up and says “Bazinga punk, now we’re even!”