Christine's 8-year-old son, Ritchie has been accepted into a posh private school where Christine encounters two snooty class moms, Marly and Lindsay, who can't seem to grasp the concept that Christine actually works. Her 20-something slacker brother, Matthew, lives with her, but in a pinch, also serves as Ritchie's babysitter.

On the first day at Ritchie's new school, Christine is mortified to discover that her ex-husband, Richard, with whom she gets along even better than when they were married, is dating a young, nice, impossible-to-hate woman also named Christine… the "new" Christine.

When Christine learns that Richard and "new" Christine are enjoying an intimate relationship, she becomes determined to make her own conquests. After several failed attempts to meet eligible men, she finally runs into a guy named Stan at the grocery store. Unbeknownst to Christine, Stan is a father at Ritchie's school who is known as "Sad Dad."

Richard learns from a gloating Matthew that Christine is out enjoying her fifth date with a new beau, Burton, so he does what any self-respecting ex-husband would do: he sabotages the happy couple's goodnight kiss and insults Burton with lawyer jokes. But when he tries to make it up to them by inviting Christine and Burton to dinner with him and "new" Christine, his best-laid plans go awry.

After 10 dates, Christine faces a critical moment in her relationship with Burton. Will she or won't she? Let him in the house, that is, to meet her son, Ritchie. She eventually relents, only to be thrown for a loop later.

Concerned about the uniformity of Ritchie's schoolmates, Christine takes it upon herself to help diversify the student body at his private school.

Following Christine's breakup with Burton, everyone expects Christine to fall apart emotionally, but she insists she is fine and looking forward to spending time with her best friend: "me." But after being humiliated while dining out alone, Christine realizes she really did care for Burton, which drives her even crazier.

Christine feels pressured to throw an extravagant party for Ritchie's 9th birthday, his first involving other children from his new private school. Recoiling from sticker shock after meeting with a ritzy event planner, Christine decides to have an arts and crafts party at her home, with mixed results.

Christine tries not to have a meltdown when her ex-husband, Richard, brings his "new" Christine with him to pick up Ritchie and take him to breakfast so that they can get to know one another. By day's end, Christine tries to pull herself together to make a good impression at parents' night at Ritchie's school, but is caught off guard when "new" Christine shows up as well.

Christine's former marriage counselor comes into the gym, leading to some awkward moments between the two women. When Christine mentions this to Richard, his cryptic reaction leads her to question whether it was in the counselor's best interest to encourage their divorce. Meanwhile, Matthew finds Christine's wedding video in a box of old photo albums, and Christine takes a trip down memory lane.

Christine objects when Richard and "new" Christine want to take Ritchie to a Rolling Stones concert. Fearing that Ritchie is too young to be exposed to sex, drugs and rock and roll vices on display at a Rolling Stones concert, Christine initially forbids it. Eventually, she relents but immediately regrets her decision and, in a panic, goes to the venue with Matthew to see if she can sneak into the concert in order to keep tabs on Ritchie.

Shut out once again by the cliquey, judgmental moms at Ritchie's school, Christine runs into a down-to-earth working woman, Belinda, who invites her over for a drink after work. Belinda's job, however, isn't quite the type of position Christine expected her to hold, which throws yet another wrinkle in her attempt to fit in with the other school parents.

Christine volunteers to help out at Ritchie's spring carnival and while there, she runs into the mean moms -- Marly and Lindsay -- who are clucking over the attractive father of a new student at Westbridge. Christine is excited to learn that the hot dad is her ex-boyfriend, Burton, but her hopes of re-igniting their romance are shot down when she learns Burton has a new girlfriend.