Allison is Don's secretary at the original Sterling Cooper and later at Sterling Cooper Draper Pryce. Following Don's divorce from Betty, Allison becomes involved in his personal life, even buying the presents he gives his children. When Don drunkenly leaves his keys at the office Christmas party, Allison delivers them to his apartment. Her act of kindness evolves into a sexual encounter that leaves Allison aglow, but the next day Don perfunctorily thanks her for the keys and hands her a cash Christmas bonus.
Despite her disappointment, Allison attempts to maintain a professional demeanor. Her emotions overtake her, though, when she participates in a Pond's Cold Cream focus group with other SCDP secretaries. As Don watches through a two-way mirror, the women describe their love lives and disappointments. Allison runs out of the room in tears, lamenting privately to Peggy how Don "turns on the charm and then yanks it away." Soon after, Allison resigns and asks Don for a letter of recommendation. “Type up whatever you want, and I'll sign it," Don replies. Allison hurls a paperweight at him and stalks away.