Sheldon and Raj consider researching dark matter in an abandoned salt mine. Their friends are quick to remind them of the claustrophobic and challenging conditions for which neither of them are suited. 

Penny sold the car Leonard bought for her since she now has a company car. She gives him the money and a pink framed photo to remember it. He returns the money to her because the car was a gift. It goes back and forth until Leonard ends up with it. He comes up with a solution -- their first joint bank account. Penny agrees that's a good idea.

Raj goes to Sheldon and tells him about the harsh conditions in the mine. He suggests that they simulate the environment and see if they can handle it. They head into the steam tunnels under the university while Amy sits above them for protection. Sheldon struggles and starts singing about the mine. Raj mentions Miley Cyrus and ends up telling him about Hannah Montana.

Leonard and Penny go to Bernadette and Howard for advice about handing money issues. Bernadette reminds them all that she makes a lot more money than her husband. He mentions he bought a collectible and she gets upset he did it without permission. Then, they end up arguing about chores. Howard has a chore chart and gets a star for completing them. 

Bernadette threatens his allowance, which infuriates Howard. He insists it's a stipend and that she broke the promise to not discuss his allowance in front of his friends.

Amy calls down to Sheldon to see if they wanted anything. Raj tells Sheldon they could bring stuff with them, so they ask her to get them Funyuns, pop and portable DVD player and Hannah Montana.

Penny worries that if she makes more than Leonard, they'll have the same problems. Leonard assures her that won't happen, because his mother emasculated his father and that's what love looks like. Penny and Leonard use this experience to learn what not to do.

Sheldon confesses he feels like he's starting over now that he's switched topics. Sheldon rushes out of the tunnel when he see a couple rats walking behind Raj. He takes off with Amy and leaves Raj behind. He lasted 11 minutes in the tunnel.

Penny and Leonard spread the money on their bed and decide to have fun with the money. Bernadette and Howard make up. Amy transcribes Sheldon's experience. Raj shows up at Sheldon's upset and all dirty from the tunnels. Raj calls Sheldon selfish.