What My Bones Know begins with Stephanie Foo’s diagnosis. She is living in New York City when her therapist from San Francisco, whom she has worked with for eight years, finally tells her she has complex PTSD (C-PTSD). At 30 years old, Foo often worries that her depression and anxiety, which she developed at 12, prevent her from easily forging interpersonal connections. She agonizes over her interactions with others and feels that she lacks empathy.

Samantha, her therapist, explains over Skype that complex PTSD is different from traditional PTSD in that it is not the result of a single instance of trauma. It instead develops through repeated instances of traumatic experience, and it is often the result of child abuse. After Foo scours the internet for information on the condition, she realizes that many of the symptoms of C-PTSD describe her perfectly. Foo decides that she cannot run from her past anymore and must face her condition head on by revisiting her childhood.

Foo returns to her childhood home in San Jose and reviews some home videos taken during her youth. Although the tapes depict a loving family, they do not capture the darker moments of her childhood.