Beckett worries that the room full of detectives she works with will figure out she and Castle are together. That's why she tries on several different outfits for her first day back on the job. Castle doesn't mind. He totally digs watching her undress. Beckett orders him to act normal. Castle fails this assignment miserably when he shows up at a murder scene without a coffee for her since he knew she already had one. Oops!
Mandy Michaels, the weather girl for WHNY, is found shot to death behind an outdoor fountain. A still-feuding Esposito and Ryan track the victim's stolen phone to a guy who has a history of stalking, but he's no killer. A threatening note is found in Mandy's wallet. It reads: "If any of this gets out I'll kill you." Lanie says the killer tried to make things look like a mugging. She also deduces that Beckett is having sex judging by her glow. She just doesn't know the mystery man is our favorite mystery man.
Castle and Beckett check things out at WHNY. They learn Mandy had a scuffle with the new meteorologist, Rebecca Fog. Yes, that's her real name. Rebecca thinks Mandy was a lazy, entitled, big-boobed bimbo who was ticked because her coworker stole a bunch of her meteorology equipment. She alibis out for the murder. While still at the station, sexy entertainment reporter Kristina Coterra ropes Castle into doing a TV interview at a later date. Beckett suspects this lady is looking for some exclusive close-ups outside the studio, too.
WHNY's makeup ladies say that Mandy had a secret man in her life. This would be the married pro basketball star Reggie's Blake. Ryan and Esposito are sent to bring him in. That doesn't go so well. They get into a major brawl with the star's bodyguards. Ryan and Espo are a scary-looking bruised-up pair by the time they bring in the hoops star and his entourage. As it turns out, Reggie and Mandy were just friends who were on hospital charity board. He says she really cared about sick kids and was in the emergency room herself recently.
One of Mandy's fellow reporters, Miles Haxton, says he was having a secret affair with Mandy. They kept things on the qt because workplace relationships always implode. Castle and Beckett can't really hide their worried looks when Miles says this. They need to keep their relationship secret. To keep up the ruse, Castle accepts Kristina Coterra's on-air request for a date. Beckett is not thrilled.
Castle and Beckett learn that Mandy used the station's chopper to fly over New Jersey with Rebecca Fog's equipment. Her trip was cut short due to a severe asthma attack. She discovered high levels of a dangerous chemical being pumped into the neighborhood. Cazuli Carpeting is a company that has been pumping the poison into the air. The hotheaded owner sent the threatening note to scare the weather girl away, but claims he didn't kill her.
The team deduces that Mandy had a partner. They'll have to figure out who it is without our favorite mystery writer, as he has a date with a hot reporter. Castle does his best fight off Kristina Coterra's attempts to seduce him at his apartment. He's no match for this wanton woman as she straddles him on his couch in her bikini. Beckett bursts into the place believing her partner is in trouble. Castle tries to soften the shocked look on Beckett's face by letting her know that he knows who the killer is.
Beckett can't seem to shake the image of another woman's bikini-clad cleavage being shoved into Castle's face. The fact that he figured out who the killer is seems totally secondary. Still, they head down to the station to arrest Miles Haxton. Kristina told Castle that she couldn't bikini-seduce him in the past because he's gay. He killed Mandy because she wanted to expose the story they'd been working on to save the kids, but this would take place before he could get credit for the exclusive. Case closed.
Back at the station, things are awkward between Castle and Beckett. All is better with our other favorite partners though once Esposito realizes that Ryan took a punch for him during the Reggie Blake brouhaha. As for Castle, he apologizes to Beckett. They ultimately agree to talk about dating other people without "actually" doing so to keep their secret. Of course, Beckett still has to get rid of that image of Kristina's breasts in Castle's face, which reveals a devilish smirk when she says this.