Hope sits up in her bed saying that they need to stop doing this because they are going to get caught. James sits up and says what the big deal is. Hope says that she doesn't want to be like any other girl he dated, and he says she isn't, but she knows he is lying. Katie knocks on the door and Hope shoves James onto the floor. Katie comes in and asks what the noise is and Hope says that it must be the neighbors. Katie jumps on the floors and yells shut up to them. Katie says that she is making pancakes and wants to know if Hope wants any. She says yeah, and she will see Katie later. Katie asks if she wants to know what happened at David's. She says yeah, but after only a few words she says it was a great story, cutting her off. She says that they will talk later because she is really busy, in her mind. Katie doesn't understand, but says ok. As she goes to leave she notices the can of whipped cream on Hope's dresser. Hope tries to cover up the fact that her and James uses it while having sex, so she says that she binges at night. She says that she is addressing the problem and then Katie leaves. James then remarks that they haven't had sex on the floor yet and Hope just smiles and throws a pillow at him.
Katie goes into the living room where Mark is talking to Jackie, leaving her many messages because the answering machine keeps cutting him off. James sneaks out of Hope's room just in time to hear the rest of Mark's hilarious message to Jackie. He then jokes saying it's hard to believe Jackie isn't calling Mark back. Katie then quickly asks Mark about life, how's acting, and if he is seeing Jackie again. He says that acting is good, but he can't get a hold of Jackie, and he says that is too bad. He asks how things are going with David, and she says great, but it is a little weird too. She asks Hope if she agrees but Hope isn't paying attention because James is tickling her. Katie tries to continue the conversation, but Hope has no idea what she is talking about. Katie asks what has gotten into her, and she mistakenly answers no one has gotten into her. James then makes a joke about crabs in reference to Mark's hilarious message.
Mark goes to Thom for advice saying he doesn't know what he should do about Katie, especially with David and Jackie in the picture. However, Thom can't concentrate and is too focused on how hot Jackie is. Thom tells him to do what he was going to do for Katie and do it to Jackie. Mark goes to leave, and as he opens the door Alyssa stumbles in. Alyssa gets angry at Thom, slaps him and then hits on Mark.
Back at the apartment, Hope and James are in Hope's bed where there is a knock on the door. Hope shoves James onto the floor and Katie walks in saying that she heard the noise again, but Hope says she didn't hear it. She then tells the neighbors to shut up again. Katie says that she is going over to David's again, and this time she is going to go into his apartment. She asks Hope if she wants to know why and to help her pick out an outfit, but Hope doesn't want to, saying she is sleepy. Katie says that she is going to go look for something in her closet, and James quickly tries to hide under the bed. Hope tells her not too since that is where she hides her night food. Katie says that they will get her through this, and then she leaves. James starts laughing and Hope throws a pillow at him.
Mark leaves yet another message to Jack. James sneaks out of Hope's room and listens to the conversation. He tells her to stop calling her and just go over to her place. She asks why he should and James says that Katie already went to David's. He runs out saying he is going to stop being a chicken. Hope gets mad that James said something that Katie told her while he was hiding. James likes her mad and they rush into her room and have sex again.
Katie goes back to wear David lives and gives the doorman muffins. She apologizes to the doorman for the previous night and then says that this time she is going to go and talk to David. He asks to see a picture of Mark to compare, but Katie doesn't have one. She says that it doesn't matter because Mark keeps calling Jackie.
The doorman ask who Jackie is, and Katie says that she is Mark's ex. He says that she must be out of Mark's league, and because she is an astronomer, she must be a slut. Katie says that she is done thinking about it, and David is the one for her and for the doorman to ring for him. However, David walks out of the elevator with a girl named Jackie, which surprises Katie. Jennifer says that she will wait outside. Katie tries to cover up the real reason why she came by giving him the muffins she made for the doorman. Katie says that he said he would wait for her, but David says that he couldn't wait forever. Katie says that it hasn't even been a week since they had dinner. David says that it just isn't the right time, and he leaves saying that he will see her at work on Monday.
Katie thanks the doorman for his help, and he says that she should bring him a picture of Mark because he doesn't have a TV at the desk and her life is his amusement. Meanwhile, Mark decides to bring a bouquet of flowers to Jackie's apartment. Mark gives her the flowers and asks why she didn't return his calls. She says that things were moving too fast and she wanted to slow things down. Mark asks if he can come in, but Jackie says that it probably isn't a good idea. However, they end up having sex. Mark says that he wants to see her again, but she says she can't because she is getting married.
Mark freaks out about her being engaged and the two get in a fight. Mark gets really upset about it because Jackie was the first girl to make him briefly forget about Katie. He storms out, before coming back in to get his pants and shoes.
He goes back to the apartment and looks for James. He finally finds him in the shower and although James tries to ignore him, he can't once mark says Jackie is engaged. He tells James that he is not going to make a move on a girl again and leaves. Hope peers out the shower window revealing that they are in the shower together. Mark comes back in and Hope hides. Mark tells James to make sure he doesn't make a move on a girl again, and leaves again.
Katie comes home and goes to the bathroom and tells Hope that she needs to talk. Hope tries to get rid of her, but Katie keeps talking about what happened at David's. She flushes the toilet out of anger, causing the shower to get hot and James starts squealing. She apologizes thinking it was Hope.
Mark goes back to the bathroom to talk to James, and Katie says that he can't just barge in when Hope is in the shower. Mark says that it is James. Mark calls James' name, and Katie calls Hope's name, but when neither answer they open the shower curtain and discover that Hope and James are showing together.
Mark and Katie find this hilarious and can't stop laughing at the thought of them together. Hope and Katie leave to go talk and Mark pokes fun at James sleeping with Hope. Katie asks why Hope didn't tell her about them, and Hope says that she was embarrassed because now she is one of the girls that James has done. Katie puts two and two together and realizes that Hope isn't bingeing on whip cream.
Katie asks what is going to happen with them and hope isn't sure. Hope asks if everything is alright with Katie and David and Hope tells Katie not to change the subject. Katie says that she is glad that David is with another girl because she realized that she likes Mark. However, he is all hung up on Jackie now. Hope tells her that Jackie is engaged and Katie is excited that Mark might be available.
Katie wants to know for sure if Mark likes her and tells Hope that the only way is threw someone that has a crush on Hope. Hope says anyone but him, meaning Thom.
Hope goes over to Thom's place and Thom is super excited for it. Hope asks Thom is Mark has feelings for Katie. Thom says that he has no idea. In order to get answers out of Thom, Hope begins to flirt with him and he spills the beans that Mark loves her, and that is the reason why he moved in.
Hope thanks him and then leaves. Hope runs back to the apartment and tells Katie what Thom said. Hope says that Mark must be her meant to be because things with David didn't work out. Katie is excited for this and goes out to the living room to talk to Mark.
She tries to start a conversation and then asks Mark if he wants to go to the bar and have a drink and talk. Mark happily agrees and they go to leave. As Mark opens the door, Jackie appears in her wedding dress and says that she left her fiancé at the altar. Thom then runs up and tells Mark that Hope came over to his apartment. Mark and Katie look awkwardly at each other as the episode ends.