December 7, 1941, San Francisco is on high alert following the attack on Pearl Harbor and the Mulligan family is grappling with the news that Peter, beloved son and brother, is among the missing. Each of the Mulligan sisters Bridget, Margaret, Colleen and Molly strives to find her place in the rapidly changing world in these early days of World War II. With their father ailing, Margaret takes over management of the family's grocery store trying to keep hoarders at bay while daydreaming of a June wedding. Meanwhile Bridget focuses on her board exams and hopes to be accepted as an Army nurse. Beautiful Colleen, the "family flibbertigibbet" just wants to have fun despite the dire news of the war. But it's the "baby" fifteen-year-old Molly who seems to be the glue that holds the family together. With siblings, friends, and beaus being shipped out weekly, the remaining Mulligans quickly realize that this war will be fought on two fronts at home and overseas. Each of the strong, hopeful Mulligan sisters will do their part if they hope to see victory and the end of the war.

In 1942 San Francisco, war has touched every part of the Mulligans’ lives. With their brother killed at Pearl Harbor, their father recovering from tuberculosis, and their eldest sister a nurse in the Army, those at home are left to keep on, wondering if it’s possible to thrive…or only to survive. Pragmatic Margaret struggles with the gap between the dreams she’d always fostered of married life and the reality of having a husband an ocean away—combined with the concerns for the family store in uncertain times. Colleen has always been considered the superficial sister, but when a chance at her dream of Hollywood makes her second-guess her hopes and tragedy shakes her to her core, her family sees a side of her they never expected. Molly, always the hopeful one, dedicates herself fully to the war effort at home—but can all the optimism in the world guard her against harsh reality? Who can she talk to when troubles come? Each of the Mulligan sisters must do her part to keep the family going—and each must find her own new place as the world shifts under their feet and time goes by.

By 1943 the world is in the thick of war and the home-front continues to play a vital role. The Mulligans of San Francisco do their part in the war effort, but hardships and deprivations are taking a toll and each the four Mulligan sisters are tested in their own way. The war years urge young Molly to grow up quickly. Besides playing family 'war correspondent,' Molly manages the victory garden, finishes high school, and takes an internship at the newspaper. Meanwhile Bridget, an Army nurse in a dangerous region of the South Pacific, is attracted to a young doctor but so are all the other nurses. Margaret runs the family store, but suffers the loneliness of a single parent as she cares for her young son and frets for the welfare of her husband Brian as he serves on the European front. As an up-and-coming movie star, Colleen's life might appear glamorous, but film making comes with its challenges she tries to conceal her grief over her lost flyer as she helps out in the famous Hollywood Canteen. Each of the Mulligan sisters grow stronger more capable as the war wages on working and hoping and praying for victory.

Now in its third year, World War II still rages, taking its toll on everyone. On the home-front, the Mulligans continue to face war-related challenges . . . and patience wears thin. Margaret is pulled in various directions as she attempts to care for her toddler and disabled husband Brian, who’s haunted by mistakes made on the battlefield—and their marriage is put to the test. Colleen is still pursuing her Hollywood career, but will the arrival of her baby change everything? And with Navy pilots being shot down daily, will Geoff escape the odds and make it safely home? Bridget still serves as an Army nurse in the Pacific front, where not only her life, but health and heart are in harm’s way. Molly continues to do her part to help her family and find her place in the world, but when her relationship with Patrick gets shaken to the core, she heads off on a journey that leaves her family conflicted. The war will eventually end, but will the Mulligan family remain intact when it does?