In "Classy Christmas '', Holly returns to Scranton to fill in while Toby is away at jury duty. The initial excitement about seeing her old friend again turns to anger when a jealous Michael vandalizes her Woody doll (a gift from her boyfriend AJ). Holly divulges to the women of the office that AJ wo n't commit, and she 's going to give him an ultimatum to propose to her by New Year 's. When Pam tells Michael, he is cheered up by the news, as well as Holly lying to AJ about how Woody got damaged.
what episode does holly come back to the office
"Classy Christmas ''