Andy's in his office with a potential client. He dashes out to the front desk to ask Erin to help him with a trick to impress the would-be customer. He asks Erin to interrupt him in a couple of minutes, claiming he's got an important call. Andy will then refuse to take the call - impressing the client with how important he considers their meeting. Erin doesn't quite understand, but Andy tells her to just make something up; finally, they're in cahoots. As Andy butters up the client, Erin bursts in to announce there's an important call. Andy tells her can't take it, but Erin insists. She tells Andy it's the police: his mother is dead, hit by a bus. Dwight offers his condolences. Andy takes the fake call (Darryl's on the other end) and asks the police officer if his mother had any last words. "Make sure that your client gets the best deal possible," Andy repeats aloud.
A very pregnant Pam is training her replacement, Cathy. The new girl seems to be getting the ropes, and Pam wonders what impact she'll have while she's out. When Ryan asks Jim if Cathy's single, he replies, "I doubt it." Pam can't help but notice; a twinge of jealous curiosity bubbles up.
Ryan, Gabe, Toby, Phyllis, Oscar, Dwight and Kelly are discussing Pam's replacement in the break room when Pam walks in. She overhears then talking about how nice it'll be to have Cathy there: she's fresh, young, fit and normal. Pam teases them about how it'll be nice to have someone hot sitting at her desk while she's out. The team realizes how insensitive their talk must have sounded. They reassure her she's still attractive.
Gabe explains that pregnant women are one of men's most common fantasies. Toby goes on to mention that it's not just pregnant women who don't get their due for being attractive. He thinks Helen Mirren is hot - and all the guys agree. Toby says a pregnant Helen Mirren would be the hottest ever. Dwight, overhearing it all, calls B.S. You're salivating over a 66-year-old woman who was born a Russian national in the Soviet era, he tells them. Pam looks on: she's impressed by Dwight's intellectual honesty.
Andy invites Darryl and Kevin down to the warehouse for a little lunchtime musical jam. They're quickly in a groove, with Kevin on drums, Darryl on keyboard and Andy on guitar and vocals (singing scat from a lyric binder). Looking on, Val's impressed, as is Robert California, who has surprised Andy by showing up early for their meeting. California's intrigued by the band (which Kevin falsely claims is named Kevin and the Zits) and invites himself to join in on harmonica. The boys are excited.
Pam can't stand it. She asks Jim point-blank if he thinks Cathy is attractive. Jim says no. But in an interview he makes it clear: he would never tell his nine months pregnant wife that he considers her replacement attractive. Pam presses him, but again he denies that Cathy's good-looking. Dwight overhears and agrees with Pam: it's highly improbable that Jim doesn't find Cathy cute. Pam's convinced that Dwight is the only person she can trust to be honest with her. She offers to pay him five dollars if he'll help her catch Jim in a lie about how he feels about Cathy. It's a deal.
Dwight is serious: the only objective will be the truth, no matter the cost. Kelly offers a perfect test to determine if Jim's lying. The Matchmaker Test determines whether someone is attracted to a third party by asking the person in question who among his friends he would set up with that third party. If the person recommends a cute friend as a match, then that person definitely thinks the third party is attractive. And vice versa - if they'd choose an unattractive person to match up, they consider the person unattractive. Pam and Dwight like it.
Robert California is jamming with Kevin, Darryl and Andy when two of his musician friends stop by. He introduces them as just pals, but they're actually notables: keyboardist Curtis is a local music legend and Robert's other friend is a local sportscaster. The guys are impressed and invite Robert's friends to take over their instruments. As they begin jamming on "Midnight Rambler," another musician shows up, a woman named Lisa. She plugs in a Les Paul guitar and begins shredding. Andy, Darryl and Kevin watch from the sidelines as the musicians find a smokin' groove.
Pam tries the matchmaker test on Jim. He immediately responds that his friend Mike Tibbets would be a good fit. Pam, Kelly and Dwight look up Tibbets' Facebook profile: he's quite plain. They think Jim has chosen someone just unattractive enough to throw them off. In an interview, Jim admits that's exactly what's happened. Dwight suggests a new test: gauging Jim's physiological reaction when he's near Cathy. The body's reaction - specifically the crotch - doesn't lie. As Jim chats with Cathy, Dwight fakes an awkward fall toward him and grabs his crotch repeatedly, probing for signs of an erection. He reports back to Pam: unless Jim has unusually soft erections, there's no body response that he can discern.
Pam remains unconvinced. She's ready to try Dwight's next suggestion: a lie detector test. Pam tells Jim how annoying it is that he won't simply admit he thinks Cathy's hot - and she tells him about Dwight's idea. They all walk over to the local pharmacy and use the public blood pressure machine. Dwight tries to calibrate Jim's response by asking harmless questions. Then he asks about Cathy - and declares that Jim's lying. Pam pushes Jim to admit his attraction; he continues to deny. But upon closer examination of the readings, Pam notices that all Jim's blood pressure readings have been the same: 150 over 100. He's got hypertension.
Back in the warehouse, Val chats with Andy, Darryl and Kevin. She wonders why they've been pushed to the side. As Robert California and his friends strike it up again, the guys are feeling very left out. They walk out and find a spot in the parking lot, where Darryl and Andy harmonize on a sweet version of Frampton's "Baby I Love Your Way." Later Kevin and the sportscaster start a drum duel, but it's no contest. Robert California's highbrow pal beats the hell out of the skins as Kevin walks off in disgust.