Addie McKenna, at 23, has always dreamed of becoming a doctor. But her dreams are shattered when a devastating car accident claims her parents, leaving her to care for her younger brother Gabe (18) and sister Beatrice (13). Overwhelmed by grief and the weight of her new responsibilities, Addie is forced to drop out of medical school to support her siblings. She pushes away help from her family and friends, including her college love interest, Leo Garcia. Leo, though not an expert on family, is deeply moved when he learns of Addie's struggles from a mutual friend. Despite her refusal, he can't stand by and watch her suffer. Determined to support her, he helps behind the scenes, hoping she'll eventually let him in. He helps the McKenna's out by sending them food and getting information about Addie through her devious sister. Sister Mother explores the evolving dynamics of Addie's newfound family, her personal battles with a physical disability, and the tender beginnings of her romance with Leo. It's a powerful story of self-reliance and love that resonates deeply with young women. This novel also brings much-needed representation with its portrayal of a disabled character taking on the responsibilities of parenthood.