If you could go back and redo everything from your youth, would you? This is the question Brooke Matthews faces after she has a breakdown at her office job. At age sixteen, Brooke was institutionalized with an eating disorder, torn from her high school, and never spoke to her friends, including her first kiss Monica, ever again. Brooke had managed to deal with all this for over a decade until her mother’s death, which makes the wound still as fresh as it was at sixteen. Brooke takes a leave of absence and goes into therapy, where her therapist encourages her to reach out to Monica.

Monica Kandybowski—or Miss K to her students—has been a teacher in a Toronto suburb for the past six years. Her life is normal, if not sometimes stressful, but all this is turned around when she hears from her first crush, Brooke. The two reconnect over coffee, and soon she and Brooke decide to recapture their youth through many activities they missed out on. So when the two start to fall in love, it feels as if they are picking up the broken pieces of their past life—except now nothing stands in their way.

The truth of their youth turns out to be too hard to handle, especially as a notebook resurfaces, and the circumstances of Brooke’s departure comes into starker focus. Will past hurts get in the way, or can they have their invincible summer after all?