Felicity tells Sally that things have been going great since her first kiss with David. She finds a small dog on her way home from David's place. He doesn't appear to belong to anyone, so she takes him and decides to call him Lucky. She stops by Elena and Noel's place to ask if the dog can stay for a few days. Noel finds that he's still allergic to dogs so Lucky can't stay at their place.

Felicity's anxious to find a place for Lucky to say. Tonight she and David planned to rent a movie. This might also be the first time they have sex. Since he couldn't stay at Elena and Noel's place or the dorm, she decides to ask Javier. Javier says he'd love to take Lucky, however he must first have the approval of his cat Mommy. Javier says that Mommy is insulted that he would even consider taking a dog. Felicity takes Lucky to Sean's loft. Sean agrees to keep Lucky for a few days until he grabs a blouse from the laundry rips it up and runs through the loft knocking things over.

Julie comes in looking for her shirt. Sean tells Julie what happened to her shirt. She says she hadn't even worn it yet. She'd planned on wearing it on her date tonight with a guy named Seven.

David tells Felicity Lucky can stay at his place until she can find a permanent place for him. Felicity tells him it's so amazing of David to take him. He jokingly says, 'Finally I'm getting lucky.' Felicity asks if that's the only reason he's taking Lucky. David says , 'yeah', so he can make that bad joke. Later that night Felicity and David are in bed. He tells her he has a condom. Felicity tells him to wait. He asks if it's too soon. Felicity says ,'No.' Lucky is staring at them and it's freaking her out. She says she just can't have sex with Lucky watching them. David gets up and carries Lucky into the bathroom. He starts whining and barking. Felicity says it sounds like he needs to go for a walk. She asks David if he wants to go with her. He says some air might be nice.

Elena tells Felicity she's using Lucky as an excuse not to have sex with David. She points out that Felicity has issue with sex. Felicity denies having issues with sex. Elena asks why after nearly a year of dating Noel she never had sex with him. Felicity says she wasn't ready. Elena asks what about Ben. Felicity says she wasn't fully prepared.

Maggie stops by Dean & Deluca and tells Ben she's still interested. Ben tells Sean that maggie is married. On one hand he doesn't want to break up a marriage, but he thinks Maggie must really be unhappy, so he's like 'who cares.' Maggie gives Ben a key to a hotel room. She promises not to bore him with details about her marriage. She says if he doesn't come to the hotel, she'll never bother him again. Of course Ben goes. He notices a butterfly tattoo on her lower back and tells her he likes it. She tells him it's not the only one. He looks through her wallet while she's on the phone and sees photos of Maggie and her husband. She takes the photos from him.

Felicity takes Lucky back to her dorm room and asks Meghan to watch him while she goes out to get him some food and also dog sit him tonight while she's at David's place. Meghan agrees to do it if she can use Felicity's computer. Felicity says 'apparently' - Meghan is already using the computer. When Felicity returns the door is open and Lucky is gone. She asks Meghan where Lucky is. Meghan says she thinks he had to go pee. Felicity asks if he's supposed to pee in the hallway. Meghan says she doesn't know, but he's not going to pee in the room. Felicity goes to look for Lucky and finds him being fed beer by a couple of morons.

Since Felicity couldn't find a place for Lucky to stay , she figured it was an omen - she wasn't supposed to have sex. Elena insisted on keeping Lucky for the night with one condition - that Felicity actually have sex. Things are getting pretty hot & heavy at David's place, while Lucky is tearing up a sofa cushion at Elena and Noel's place. Noel asks why the dog is there. Elena lies telling him Felicity had to go to the library. Lucky pees on one of Noel's model houses. Felicity's beeper goes off just as David opens a condom packet. He jokingly says the condom has an alarm on it. David asks if she really needs to look at the pager. Felicity apologizes explaining that it's only for emergencies. It's Elena. Felicity calls her, but Noel answers. He tells her Lucky bit him and she needs to come and pick up the potentially rabies infected freak of nature. Noel hears music in the background and realizes she's not at the library. He tells her to stay. She insists on coming over to get Lucky. She apologizes to David.

Elena tells Felicity she should talk to Noel about her sex issues. Noel asks if she and David have had sex. Felicity says 'no' and asks if he and Ruby have. Noel tells her they have. Felicity says everyone is more healthy that she is. Noel says she's not unhealthy - she's just a romantic, which is what he loves most about her. She wants sex to mean something - it should. He tells her he's actually glad they never had sex. He says he likes Ruby a lot - it was nice, but afterwards he knew what it was like to be with her. He says he doesn't like Ruby any less, but now the mystery is gone. David calls to tell Felicity Lucky is sick - he's not eating anything.

Felicity takes him to the vet. He has a viral infection of the brain. There is no treatment so Felicity has only two choices - either let the disease run it's course or put the dog to sleep.

Felicity takes Lucky back to David's place. He's bought a new crate for Lucky to sleep in. Felicity is not in the best of moods after receiving the bad news about Lucky. She doesn't really feel like talking. David asks when she's going to stop using the dog as an excuse. If she doesn't want to be with him she should just tell him because he's been putting forth a lot of effort and she hasn't. She tells him she's right and maybe she shouldn't be there. She leaves.

Lucky has been experiencing lots of pain so Felicity decides to have him put to sleep. Noel offers to go with her. The vet gives Felicity and Noel time alone with Lucky. Felicity tells Lucky he's such a good boy. Noel says he wasn't that good. Felicity says he must have had a tough life, being alone, without anyone to love him. David shows up. He called looking for Felicity and Elena told him where she was. He says he wishes she'd told him about Lucky.

Maggie's husband comes into Dean & Deluca to order a berry cake for their anniversary. He wants Ben to decorate it with a butterfly. Ben is very nervous face to face with Maggie's husband. Her husband appears to be unaware of his wife's affair with Ben.

Felicity tells David she was using Lucky as an excuse. She tells him she slept with one other person before - it was only one time and she barely even knew him. She says she's never had sex with someone she cares about. David tells her before he met her he didn't even want to get involved with anyone and now he's spending time with someone he really cares about. He doesn't know how this is going to go, but right now they have a very good thing and he doesn't want to screw that up. He tells her if she's not ready, they shouldn't do it. Felicity feels a great weight has been lifted - no pressure. She kisses him. She tells him this is better - they can just enjoy themselves - let things happen when they happen. David says that sounds good. Felicity asks what about now.

The next day Felicity is having breakfast with Noel. He asks how things went with her and David last night. Felicity says it was good. Noel asks if the 'mystery' is gone. He says now they have something that she and David don't. They both smile.