The scene opens with Neal and Peter checking into the case of a woman named Selena, a "black widow" who has four rich dead husbands. She's on her way to New York. The deaths are listed as natural: heart attack, embolism, sky diving accident. They're waiting for the fourth results. But she hasn't filed for any of the insurance claims. There's a Manhattan Millionaires Bachelor auction coming up. Peter wants Neal and Jones to pose. They need a third. Neal suggests Peter. Peter breaks the news to Elizabeth, who reassures him he'll sell high. Sara advises Neal. He's going to have to throw his meetings with the other women so the black widow doesn't get outbid. Elizabeth tries to remind Peter he's having a conversation, not an interrogation.
At the event, Jones introduces himself as "Arthur", a pastry baron to multi-million dollar Dessert Empire. The organizer, Gerald Jameson, calls for the auction to begin. Diana is also in the crowd; she sidles up to Selena. They get five minutes to talk to each man. The mingling begins. Peter awkwardly chats up a woman from Ohio, trying to make conversation about Cleveland. Arthur talks exuberantly about pastry. Neal tells one woman he loves hunting baby deer, then interrupts her to answer his cell phone. On his next date he checks sports scores. Diana tells Peter that Selena is looking for someone sincere, but not self-assured. The guys all take turns with Selena. When it's Peter's turn, he stalls awkwardly. Then he tells her he's not up for all the small talk and just wants a real conversation.
He wishes her luck finding someone. It's auction time. A bidding war breaks out over Arthur, who goes for $11,000. Selena tells Diana he was too charming. Nobody bids on Neal. They have to lower the price, until finally Diana takes him for $1,000. Selena says he's too young. Before they can start bidding for Peter, Selena offers $15,000 and wins. Back home, Peter enjoys getting the second-highest bid ever. He plans to plant a bug in her house and be done with the op. At the office, Peter takes a call from Selena. She won't let him pick her up so he realizes he'll have to make it through their whole date and make her want to take him home. At the restaurant, Neal presents Diana with a fancy picnic in the surveillance van for helping him save face.
She suggests he should cook for Sara sometime because "Insurance Adjuster Barbie" would love it. Peter seems to be doing well with Selena inside. She asks him to dance during a slow song, but it quickly turns into a tango. Neal tries to advise him to bail, but Peter actually knows what he's doing. They dance a sultry tango. She whispers in his ear after, inviting him back to her place. She blows out the receiver in his earpiece so they can hear Peter but he can't hear them. Back at Selena's house, she goes to change. There's no computer so he can't put a key logger on it. Selena starts stripping. Peter puts a bug on her purse. Diana gets word from Jones. Selena's fourth husband died of a stabbing during a mugging. She was the only witness. Back inside, Selena comes out in a negligee and uses an ice pick to chop up ice. She holds onto it ominously as she offers Peter a drink.
He spills it on himself to get out of the situation, but she just starts helping him strip instead. Neal calls from the van with the sound effects of a factory faked in the call. Selena answers. He tells her they need him now at work. He says goodbye, but not before she kisses him and says she'll see him tomorrow night. They listen to a call she made after he left, telling a man she'll have Peter proposing by the end of the week and then it'll be his turn. Peter and Neal break the news to Elizabeth, who isn't happy he's still undercover. Neal excuses himself to meet Sara at his place. When she gets there, he has candles lit up all over. Peter picks Selena up. She announces she wants to go to his house. Peter leaves Neal a message, saying he has to clear out of his place so he can commandeer it. Neal is out on his balcony and doesn't see his phone.
He comes in to see a text from Peter just in time to shuffle Sara into a closet with wine. Neal's apartment used to be a speakeasy. The giant walk in closet has a viewing room, where he and Sara settle in. Selena sees the easels and insists Peter sketch her. He writes "help me" so Neal can see. Neal starts drawing from his closet. He apologizes to Sara for the turn in their evening. "Any guy can make a girl dinner. Only you could sketch a black widow from a hidden back room," she says. Selena asks Peter how he set up the evening. Just then, Mozzie bursts in. Peter explains Mozzie is his man "Haversham" and he set everything up. Mozzie gets what's going on and plays along, going into the closet to talk to Neal when Peter asks for his suit.
Neal finishes his drawing, but adds a final touch. Sara thinks Peter will be mad. Mozzie takes the sketch pad out with the suit Peter asked for and hands it over without Selena seeing. Then he hits Peter up for $50 "to pick up the dry cleaning" and leaves. Peter shows Selena the drawing, but doesn't notice the ring until she does. He has to go along with it. Back home, Elizabeth isn't happy her husband is engaged. He says he just needs to go along long enough to find Selena's partner. Elizabeth suggests he needs an event planner to get Selena's guest list. Cut to Elizabeth meeting with the happy couple. Selena has no list. Elizabeth understands wanting to keep it small and says her wedding got too big. Peter tries to keep his real wife happy and fake being excited about his new one. Peter leaves.
Elizabeth asks Selena if she's been married before, saying she needs the documentation for the wedding license. Outside at the car, Peter is about to get in when a car barrels at him. He jumps out of the way and is fine. Selena shoos Elizabeth away and says she doesn't know what she would do if something happened to him. Later, Peter tells Neal how the near miss led to a conversation about what would happen if he died. She says she wouldn't want any of his money, but he should leave it to charity. Peter checks her dead husband's wills. They all made large charitable contributions to organizations which don't exist anymore. Diana comes in having tracked down the fake name of the lawyer Selena gave Elizabeth. It led back to the auctioneer Gerald Jameson, who hosts dating events worldwide and moves around a lot.
Neal proposes he'll go talk to him. He brings Mozzie. Gerald says his next event is in Florida in two months. He punches in a key code for his office door. Mozzie makes note. Neal asks Gerald if he rents out his space, saying Peter asked him to host something. Cut to a raging bachelor party. Neal explains it's the perfect cover for getting into the office. Peter distracts Gerald while Neal goes into the locked office with Mozzie. They come up empty. Neal suggests there's a way to get Selena to lead them straight to the money. It will require a camera and some shots. They call Gerald over. Neal and Peter dump theirs and get Jameson loaded. Diana knocks on Selena's door and IDs herself as FBI. She tells Selena that Jameson is dead and shows her a picture.
She says she's looking into the charity. When Diana leaves Selena goes straight to the bank. Jones calls Jameson and he wakes up on the floor of his office to a fraud alert on his phone. Selena leaves the bank with a bag. Jameson meets her on the street. They're quickly surrounded. They show pictures of the night before, which included Jameson bragging he had a big payday coming. They have it all on tape. Selena tries to suck up to Peter, saying she thought they had something. "At least the tango was real?" she pleads. They take her away. Peter mentions the arrangements for the wedding are all booked. Jones goes to get Elizabeth, telling her Peter needs her help right away. She meets him in Neal's totally made up apartment, draped with lights and gauze and candles. He apologizes for what she went through and says he's giving her the small wedding she already wanted, getting down on one knee to ask her to marry him again. Mozzie, who says he has been ordained twice, serves as officiate. Elizabeth couldn't be happier.