Grieving for her older brother Lucas, Oakley Nelson agrees to spend a few months with her mother at Aunt Jo's California beach house, where a notebook of letters from Lucas to Oakley challenges her to feel better and enjoy life, but a budding romance reminds her of the chances Lucas will never have.

Flying to New York to talk their estranged birth mother into donating a kidney to her younger sister, eighteen-year-old Mia Cox forms an unexpected connection with her seatmate, a famous rock band's runaway lead singer.