Agnes doesn't know it, but she only has one hundred days left to live. When she was just a baby, she was diagnosed with Progeria, a rare disease that causes her body to age at roughly ten times the normal rate. Now nearly sixteen years old, Agnes has already exceeded her life expectancy.

Moira has been Agnes’s best friend and protector since they were in elementary school. Due to her disorder, Agnes is still physically small, but Moira is big. Too big for her own liking. So big that people call her names. With her goth makeup and all-black clothes, Moira acts like she doesn’t care. But she does.

Boone was friends with both girls in the past, but that was a long time ago—before he did the thing that turned Agnes and Moira against him, before his dad died, before his mom got too sad to leave the house.

An unexpected event brings Agnes and Moira back together with Boone, but when romantic feelings start to develop, the trio’s friendship is put to the test.