Michael hates the changes that Dunder Mifflin's new owner is implementing, so he turns to David Wallace for advice. Jim and Pam find the perfect day care center, but Jim's mistake threatens to ruin the interview.
Sabre's CEO wants the Scranton branch to have one manager, and Michael voluntarily steps down and lets Jim become the boss when he finds out that salespeople make more money. However, he soon comes to regret the decision.
Pam goes into labor and Jim is ready to take her to the hospital, but she refuses to go. Meanwhile, inspired by Pam and Jim's baby, Dwight and Angela try to reach a "business agreement" to have a baby of their own.
After the baby is born, Pam has trouble getting the baby to breastfeed. At the office, Michael takes credit for hooking Jim and Pam up, and tries to do the same thing for Kevin and Erin, making Andy jealous.
It's St. Patrick's Day, and the CEO forces the office to work late because she won't leave. In addition, Michael unsuccessfully tries to suck up to his new boss, and Andy and Erin's first date is delayed because Erin is sick.
Oscar gets everybody in the office to go to Happy Hour so that he can hit on a coworker in shipping. Pam tries to set up Michael with a friend at the bar, but Michael's alter ego, "Date Mike," threatens to spoil the entire evening.
Michael is hopeful that a potential client is interested in him, but everyone in the office except Pam thinks he's wasting his time. Meanwhile, Dwight recruits Kelly to apply for the Sabre minority management training program.
Michael becomes convinced that Donna is having an affair and puts Dwight on the case, but Pam soon discovers that the suspicions may be true. Meanwhile, Darryl gets revenge on Andy for an earlier incident.
Michael continues to see Donna even after learning she's married and meeting her husband, Dwight and Angela take their baby contract to an arbitrator, and Jim and Pam struggle to stay awake at the office.
Jo comes to the Scranton branch to find the whistle-blower. However, three different people have confessed to Michael, Michael is protecting them, and the person most people think is the culprit is keeping his mouth shut.
Everybody demands that Michael fire the new office assistant, but he won't because he's his nephew. Meanwhile, Pam tries to play a prank on Dwight, who has bought the office building, to make up for ruining Jim's prank.
Andy invites the entire office to watch him in the community theater production of "Sweeney Todd," but Erin decides to babysit for Jim and Pam instead, and Michael is upset because he auditioned for the lead and didn't get it.
A herpes scare causes Michael to get back in touch with his ex-girlfriends, where he decides to reevaluate those relationships. Meanwhile, Andy tries to teach safe sex to his officemates, bu the has a clear ulterior motive.
It's Halloween at Dunder Mifflin, and Michael is upset that Darryl went over his head with an idea, and Jim and Pam are obsessed with finding out why Danny didn't call Pam back when they were dating four years ago.
During Jim and Pam's daughter's christening, Michael becomes upset over the lack of family-like unity between himself and his employees. So he responds by impulsively joining a teenage church mission to Mexico.
Michael sabotages Erin's "Glee" viewing party because of his contempt for Gabe, Jim and Pam discover that Dwight can keep their daughter from crying, and Andy has a bad reaction to a mixture of wine and a Japanese stimulant.
Some co-workers who invested in Ryan's Internet venture want him to sell, but Michael refuses to go along. Meanwhile, Jim loses his motivation to work when he reaches his commission cap, and Dwight creates a hay festival in the parking lot.
Pam stands up to Dwight when he makes cutbacks to save money in the building, but will Dwight have the last laugh? Meanwhile, the office is surprised and energized when Michael outsmarts Oscar in a debate about China.