Wintergirls

I am the space between my thighs, daylight shining through. Lia and Cassie were best friends.  But something went wrong and Cassie changed.  Now Cassie is dead and Lia has thirty-three unanswered calls on her phone, thirty-three messages from her ex-best friend, all sent the day she died. How did she die?  Why did she cut herself off? While Lia searches for answers, she drives herself...