Johnny's Girl follows Johnny Carter, a laid-back mechanic whose world is turned upside down when he becomes the legal guardian of his teenage niece, Samantha "Sam" Carter, after her parents' tragic death. The story explores Johnny's struggles to connect with Sam as they both navigate grief, responsibility, and their new life together. Over time, with the help of his friends and through trial and error, Johnny learns that being present and supportive is more important than being perfect. Together, Johnny and Sam slowly begin to heal and form a deeper bond.