The gals' already tenuous friendship spirals toward dissolution when Dee Dee celebrates the end of her school year by hosting a raucous celebration that keeps Mona awake all night. Things get worse when Dee Dee installs a hot tub, which floods Mona's apartment. Stepping in to mediate, their father, Charles, reminds them that ""like it or not, we're family."" But the squabbling continues, until a medical emergency involving their dad arises.

Mona tries to find time alone with Nick, but her mother and Dee Dee can't seem to get the message. Dee Dee's longtime friend Aurora comes for a visit. She was once extremely obese, but has now experienced a dramatic weight loss, thanks to a gastric bypass surgery. She is not used to having men pay attention to her, and Dee Dee worries about the fact that she seems to overreact whenever someone pays her a compliment. Meanwhile, Spencer tries to get over his break-up with Camille by hooking up with virtually every woman in the Bay Area. Dee Dee tries to keep him away from Aurora, as she believes she could get hurt. Adam is upset when everyone begins to bail out of his big ""28th"" (or 27th, 26th, 25th or 23rd) birthday bash in Las Vegas. Spencer and Aurora wake up naked and hung over in a Vegas hotel room, and Adam tells them they got married. A panicked Dee Dee, unable to find Aurora, interrupts Mona's romantic weekend with Nick. They learn what has happened to Spencer and Aurora

Mona dates a hunk whose looks almost compensate for his lack of brains. As a result, she tries to hide him from her friends and family, but the effort is for naught when they're invited to her father's dinner party for a U.S. senator.

Aspiring politician Ron Brown shows up at Mona's door in search of votes, and takes a liking to her. Phyllis quickly pushes him to ask her out, and they agree to a date. Mona then learns that Big Dee Dee recently arranged a date for Dee Dee and Ron, who have been friends since childhood. The sisters are unsure about dating the same man, but their mothers insist that it will be all right (as it is unlikely that both will be compatible with Ron). Phyllis and Big Dee Dee treat the whole thing as a personal competition. Mona and Dee Dee like Ron, but decide that he isn't worth the potential damage to their relationship. They agree to do the ""mature"" thing and stop dating Ron, but each keeps seeing him behind the other's back.

Mona and Dee Dee agree to get each other dates as a birthday present. Dee Dee does some thorough research and finds Mona a seemingly perfect guy, James, and the two get along well enough to set up a second date. Mona waits until the last minute to begin her search and is forced to turn to a less-than-helpful Spencer and Adam as she tries desperately to track down someone for her sister. Meanwhile, Dee Dee convinces a reluctant Big Dee Dee to let Mona and Phyllis join them for a mother/daughter portrait sitting. Big Dee Dee and Phyllis see the photograph as another opportunity to outdo each other and go all out to find the flashiest outfits possible.

In an attempt to win Mona's respect and stop living off her father's largesse, Dee Dee takes a job as a waitress. Meanwhile, Phyllis persuades Mona to give a video-dating service a try.

Dee Dee runs into Clay, her ex-boyfriend with the foot fetish. He tells her that he has gotten treatment for his problem, and asks to start seeing her again. Dee Dee is not interested, but Mona and Big Dee Dee convince her that he is a good guy who deserves another chance. Dee Dee follows their advice and is very happy with Clay. However, Mona and Big Dee Dee catch him rolling around half-naked with a bunch of Dee Dee's shoes. He begs them not to share this with Dee Dee, but quickly has another relapse. Meanwhile, Spencer may lose his job after he fails to clear samples on a new album. The original artist, funk singer Otis Wright, has no interest in allowing the use of his music. However, Spencer catches a lucky break when Otis develops a mutual attraction with one of his biggest fans, Phyllis.

Mona fears that Chase hasn't made any special plans for Valentine's Day, so she tries to take action. Dee Dee sets Brett up on a blind date in the hopes of curing him of his bad mood concerning the holiday, which stems from a broken engagement. Spencer gets close with a rival music executive whom Mona despises. Adam grows irritated with his Valentine's date, a man with whom he's shared a yearly tryst for the past 10 years.

Mona continues to bristle at Spencer's relationship with Naomi, who seems strangely reluctant to become romantically involved with him. Mona's mother and friends encourage her to put her personal feelings about Naomi aside and help Spencer. Naomi later divulges a surprising secret to Spencer. Dee Dee has difficulty following her boss' edict to drop a female tennis player with limited marketability. Big Dee Dee gets a potential break in her acting career when she's given a callback for a low-budget horror movie.

Dee Dee invites Mona to a ""girls night"" with her friends, but Mona instantly feels out of place amidst the ritzy women. When Dee Dee gives Mona an expensive purse, Mona deduces that her half-sister is trying to make her over. Meanwhile, Spencer is attracted to one of Dee Dee's friends.

When Mona and Dee Dee set Spencer up on blind date with a woman they met from the gym, Spencer falls for her hard and fast. But when Mona finds out the girl is only using Spencer to get back at her ex, she tries to warn him -- only he thinks Mona is jealous.

Dee Dee has difficulty finding a job after graduation. After she announces plans to return to school, her fed-up father not only cuts her off, but orders her to pay back all expenses accrued since her 21st birthday. Mona begins dating her handsome and charming new neighbor, Lorenzo, but her insecurities stand in the way of the relationship. Spencer changes his wardrobe in the hopes of getting people to take him more seriously.

Dee Dee and Big Dee Dee plan a ""surprise"" party for Charles and Big Dee Dee's 24th wedding anniversary. While putting together a slide show, Dee Dee discovers that there are very few photographs of Mona with their father. She feels sorry for her sister and makes several attempts to cheer her up (first creating fake photos of the two, then trying to set up a lunch date for Mona and Charles), but only angers her further. Mona explains that she had accepted the fact that she and her father didn't have the closest relationship, but Dee Dee is inadvertently opening the wounds. Phyllis produces evidence that proves Charles wasn't quite as distant as it seems. Spencer develops an attraction to Camille, a photographer working with Delicious Records artists. Adam constantly tries to alert Mona about Spencer's feelings for her. He finally tells her the truth, but they discover that Spencer is involved with Camille. Meanwhile, Dee Dee becomes annoyed when her ""summer fling"" starts to get

Mona pretends that Drew is her son in the hopes of winning over an artist that she is trying to sign who is a single mother. After her plan fails miserably, she suggests that Delicious stop chasing after artists that they have no chance of signing and instead conduct a talent search. Spencer continually bad-mouths all of Mona's ideas, and the two snipe at each other. Adam advises Spencer to finally deal with the tension between Mona and him before it destroys their friendship. Meanwhile, Dee Dee obsesses over trying to build a cabinet without any assistance; and Big Dee Dee drives Charles crazy when she tries to get over her depression by scheduling lots of ""quality time"" for them as a couple.

Dee Dee is furious to discover that Mona has become friends with Dee Dee's rival, Stephanie Seymour, after meeting her through a work event. Dee Dee insists that Mona should dislike the same people that she does because it is her duty as a sister. Mona tricks the duo into having tea with her in the hopes of getting them to make peace, but things do not exactly go the way she had planned. Meanwhile, a rejected applicant for the talent search refuses to take no for an answer.

Mona panics when a screw-up by Spencer may cost Delicious a chance to have mega-successful producers Jimmy Jam and Terry Lewis help judge a showcase with the talent search finalists. Meanwhile, Dee Dee tries to prove to Mona that she can get by without their father's assistance after she gets downsized from her new job before her first day.

Dee Dee attempts to get closer to Mona by planning a joint birthday party, reminding Mona of bad memories from their childhood. Meanwhile, Dee Dee unwittingly reveals that Phyllis lied to Mona about things that have shaped her world view since she was young; and, as a birthday gift, Phyllis finally tells Mona the truth.

Dee Dee persuades Mona to attend a banquet that's being held in honor of their father, but the experience reminds Mona that she's the odd one out within her dad's ""new"" family.

While at a club with Spencer, Mona meets the hunky Miles. They hit it off, but their budding romance quickly trips up over matters of taste: For one, she enjoys Dawson's Creek, while he prefers BET. After a night on the dance floor, where Mona displays her lack of rhythm, Miles breaks up with her for not being ""black enough."" In an attempt to win him back, Mona remakes herself into what Dee Dee calls ""a Nubian disco queen.""

Spencer continues to shower Naomi with affection after she reveals her HIV-positive status. However, her newfound confidence prompts her to dump him and seek to profess her love for another man. Mona tries to comfort Spencer, but he rejects her for failing to back him throughout the relationship. Dee Dee agrees to join her new actor boyfriend in a reality show, and winds up humiliated. Charles is surprisingly supportive when Big Dee Dee is asked to do a nude scene in her film debut.

Mona returns from a Hawaiian vacation and clears the air with Spencer. They reaffirm their decision to just be friends. While looking through some vacation photos with her family, Mona reveals that she can now ride a horse. She is stunned to learn that Dee Dee still has the horse their father gave her as a child, Daddy's Favorite, and that she has lied for years about having not kept the horse. (The horse led to a major rift between Charles and Phyllis that separated the sisters for a decade.) Mona decides to buy her own horse, but it doesn't quite go as planned. Meanwhile, Adam helps Spencer uncover the cause of Kai's sudden unpleasant attitude toward him.

Mona's music-video shoot for a rapper may end in disaster when he refuses to leave the dressing room—until he meets Dee Dee. While Mona is pleased with the rapper's newfound enthusiasm for the shoot, she soon begins to worry that he's using Dee Dee.

Dee Dee is smitten with her new beau, but the romance sours when she learns that he and Mona dated in high school. Although Mona gives her blessing to the union, she soon changes her mind.

In a strange reversal of fortunes, Dee Dee's charmed life seems to hit an unlucky streak at every turn while, ironically, the usually pessimistic Mona's life becomes auspicious from one moment to the next. When Dee Dee starts doubting herself after failing her assigned mock-court competition at school, with Mona's help she manages to regain her waning confidence by confronting a crooked businessman.

Dee Dee invites everyone over to her parents' house for Christmas. The Bay Area experiences a heatwave, which leads to a brownout that nearly ruins dinner. Spencer angrily declines Mona's invitation, as the holiday brings up many issues about his absent father. Mona later offers to help Spencer track down his father. Phyllis brings her new boyfriend, a Santa Claus she met at the children's hospital, but both she and Charles object when the man refuses to keep his hands off of her. Neil calls Dee Dee and asks to come over and speak with her. She believes that he wants her back, and is stunned when he instead announces plans to marry. She tries to use the heat to her advantage in an attempt to win back Neil, while Mona urges her to just move on.