Michael tries to motivate the Scranton branch to lose weight as part of an interoffice competition. Jim is lost after Pam leaves for art school in New York, and Angela continues to see Dwight even though she is now engaged to Andy.
A confession at an H.R. business ethics seminar leads to a dispute between Michael and Holly over whether Meredith should be fired. Dwight tries to prove to Jim how long he can go without taking a personal break
Michael and Holly have sex for the first time, and Michael holds a fund-raiser for the office after it is burglarized. Dwight confides in Phyllis after Andy and Angela set a wedding date, and Jim runs into Pam's ex-fiancé Roy.
Holly is transferred back to New Hampshire after corporate discovers that she and Michael are dating. Dwight tries to apply to Cornell to get under Andy's skin. Jim's brothers and Pam decide to play a trick on Jim when they meet for lunch.
When Michael discovers that corporate has brought back Toby to replace Holly, he tries to frame him with drugs to get him fired. Meanwhile, Jim surprises Pam by buying his parents' house, and Pam files a secret complaint about the microwave.
Michael has to spend the office surplus by they end of the day, but he can't decide between a copier or new chairs. Dwight plays a dirty trick on Angela as they prepare for Andy and Angela's wedding on the beet farm.
Phyllis blackmails Angela into doing the work for the Christmas party, which Michael turns into an intervention after Meredith gets drunk and sets her hair on fire. Meanwhile, Dwight corners the market on a popular Christmas gift.
Dwight's too-realistic fire alarm gives Stanley a heart attack. When he returns, Michael learns that he is the cause of Stanley's stress. To remedy the situation, he forces the office to throw a roast for him.
While on lecture tour to other Dunder Mifflin branches, Michael and Pam discover that Jim's ex-girlfriend Karen is pregnant. At the office, Andy falls for a prospective client, and Jim and Dwight try to set up Kelly's birthday party.
Michael holds a lonely hearts party on Valentine's Day at the office, hoping that he will run into a woman he met earlier that day at a blood drive. Meanwhile, Jim and Pam have an awkward lunch with Phillis and Bob Vance.
Michael asks Dwight to be the scapegoat for one of his business ideas that backfired badly on him. But when that idea has an unexpected positive upside, Dwight still takes credit and Michael becomes furious.
Michael gets upset when he gets a new boss to act as a buffer between him and David Wallace, and he gets even more upset when he disbands the Party Planning Committee and cancels Michael's fifteenth anniversary party.
Dwight chooses loyalty to Dunder Mifflin over loyalty to Michael, which leads to a bitter battle between Michael and Dwight over Dwight's accounts. Back at Dunder Mifflin, Jim pretends to confide in Andy.
The Michael Scott Paper Company is gaining clients by offering lower prices than Dunder Mifflin, but is going broke in the process. However, Dunder Mifflin is losing clients to him, and is desperate to buy him out.
Michael returns to Dunder Mifflin and brings Ryan and Pam in as salespeople, but the existing salespeople demand that Michael return the clients they stole back to them. Meanwhile, some employees take the idea of Casual Friday too far.