It's 1949 and Julia Child (MERYL STREEP) has moved to Paris with her husband Paul (STANLEY TUCCI). He's busy working as an exhibits officer with the United States Information Agency, but she's bored and needs something to fill her time. After some unsuccessful ventures, she decides upon taking up French cooking, what with her love of eating that cuisine but inability to find any French cookbooks that have been translated into English.
After getting into the Le Cordon Bleu cooking school run by the snooty Madame Brassart (JOAN JULIET BUCK), Julia eventually meets Simone Beck (LINDA EMOND) and Louisette Bertholle (HELEN CAREY), and the three women decide to write an English language version of a French cookbook.
Little do they know that their work will later inspire and change the life of someone many decades later in 2002. She's Julie Powell (AMY ADAMS), a government call center agent who responds to citizen inquiries about most anything related to the terrorist attacks of 9/11. That line of work gets her down, as does her recent move with her husband Eric (CHRIS MESSINA) to a small apartment above a pizza parlor in Queens.
It's Eric who convinces her she should blog about her experiences, and she decides she'll do one about cooking, what with thinking she's found a kindred spirit in Julia Child. Giving herself a one-year deadline, she sets out to make every recipe in Child's Mastering the Art of French Cooking cookbook, getting support not only from Paul and her best friend, Sarah (MARY LYNN RAJSKUB), but also the growing number of readers following her blog.
As she continues her quest and must contend with various obstacles and setbacks, the story alternates between her tale and that of Child who strives to get her cookbook written and published.