i came across a copy of this arc at work a while back, before there were too many reviews of it up on here. i couldn't tell, from an admittedly cursory assessment, whether it was creepy psychological suspense or a more heartwarming story of female friendships overcoming past betrayals and reigniting when one was in need of support. i decided to pass on it, because i didn't need another book to read, especially one that i was already iffy about. and then once more people started reviewing it, and it became clear that it was, in fact, creepy psychological suspense, i was all "oops," and when the publisher offered to send me a copy, i was quick to accept because you're rarely in the position to unmake mistakes you have made, and you gotta take every opportunity to second-guess decisions and make things right. 
 which is kind of fitting, considering the themes of this book. 
 it's about two women whose paths cross years after their teenage friendship ended messily. the details of the mess are shrouded in mystery, and true to the genre, the reader is kept in page-turning suspense, teased and manipulated throughout the meat of the book, until the final reveal. 
 the book is told through alternating POVs and timeframes. heather narrates the "before" sections and edie narrates the "after." 
 in the "before," we see heather as a lonely girl - she's friendless and overweight, socially awkward and prone to violent fugue states, with an unsatisfying home life in which each family member drifts in their own path, interacting frostily, if at all. a childhood tragedy ended any expectation for emotional support, and heather's only source of approval is by doing well in school. and then edie moves to town, and she's all bold and beautiful charisma, and she and heather just click and form a fierce friendship. and then edie meets a boy, which is never a good thing for female friendships of differing social desirability. 
 in the "after", edie is a waitress whose one-night-stand resulted in a pregnancy she's going through alone, having never told the married man she slept with that he knocked her up. in the throes of postpartum depression, vulnerable and exhausted, heather suddenly arrives on her doorstep and edie gratefully relinquishes herself and her daughter to heather's care, despite the seventeen-year pause on their friendship and the reasons for their parting ways. as edie slowly comes back to herself, she starts noticing a troubling, obsessive cast to heather's behavior, and begins to actively fear for her safety. 
 the biggest trick the author manages is the trick of sympathies. both characters, in their separate narratives, are equally sympathetic. and yet you know that something devastating happened, and one of them is to blame, but suspicion shifts focus from chapter to chapter, as each character's potential to do harm/motive to hurt the other solidifies. 
 it's like Megan Abbott writing Misery, and it's nicely done. 
 the reveal makes sense both as what ended their friendship and how they became the women they became in the after. i did frown at the final-final scene, which didn't seem to make sense until (view spoiler)[i did some internetting and learned that there is no statute of limitations on sex crimes in england. (hide spoiler)] so my frown was adjusted into a thoughtful "hmmmm...." noise. 
 all told, it is very satisfying psych suspense, and i'm glad i got a second chance to give this a go.