Frustratingly delightful, The Shadow Girl masterfully leaked out hints at life-changing secrets and sinister intentions, all while keeping the reader in the dark for most of its duration. With a headstrong and confident heroine, who spends much of The Shadow Girl confused yet determined, and an interesting twist to explain Iris’ existence, The Shadow Girl is a must read for all science fiction and paranormal fans!Told from Lily’s PoV, The Shadow Girl succeeded in keeping me in constant suspense by keeping Lily from uncovering the truth to her parents’ past too quickly. With Lily’s mother being completely unwilling to answer any of her questions, Lily is forced to sneak around to discover the truth. Finding her mother’s sketches that hinted at a past Lily couldn’t remember, a trunk full of old clothes that Lily didn’t recognize but that looked to be designed just for her, and a music box that stirred up thoughts of a dark-haired, blue-eyed boy, Lily grew curiouser and curiouser; which, of course, meant I also grew curiouser and curiouser. As Iris grew more agitated, and foreign memories began to flood into Lily with growing intensity, Lily couldn’t help but question Iris’ existence – something she had always just taken for granted. Was Iris just a part of her, or had Iris somehow had a life prior to Lily? This constant state of confusion created such an intense level of suspense that I grew frustrated – in the best way – with the amount of clues that were piling up that didn’t result in answers! The Shadow Girl’s deliciously slow reveal of the truth made for great pacing as I was constantly trying to piece together the latest clue with everything else Lily had learned in an attempt to come up with the larger picture.The only thing I really had an issue with in The Shadow Girl was its inclusion of a love triangle. Considering everything going on in Lily’s life – her father’s death, her mother’s failing health and emotional distance, her depressed dog, and her questions about Iris and her parents’ big secret – I really didn’t think that The Shadow Girl needed a romantic element. And considering her friend Sylvie pretty much nails her feelings for one of the guys on the head, I didn’t think it needed to be drawn out for as long as it was.“Whenever Wyatt and I are together, I notice things about him I never did before, and I start wondering how it would be if we were more than friends [...] He’s so sweet, and nobody makes me laugh like he does. Plus, we know pretty much everything about each other, so I don’t have to worry about what he thinks.”“He’s safe, you mean.” Sylvie casts me a disappointed look. “Safe is a cop-out reason for being with someone.”That being said, I didn’t dislike the love triangle either. It wasn’t over the top, there wasn’t any instalove, and it didn’t overwhelm the plot; it was more of a background thing really, that popped up from time to time. And I actually really liked both boys, though neither of them truly blew me away or stole my heart. I just didn’t think it was necessary.So I think a big reason why I enjoyed The Shadow Girl so much had to do with how much I liked Lily. She was courageous and spunky, but vulnerable and naive at the same time. The loss of her father was something that was felt throughout the entire book, during moments when her grief would just overwhelm her for a moment, but she was always able to get past it in order to move forward. Several times she lashed out in anger because of her grief, but always recognized that she was hurting others because she was hurting, so she’d apologize for her behaviour. I loved that Archer was able to weave such an emotionally heavy event into The Shadow Girl’s plot, without incapacitating Lily because of it or using it as the thing which defined her. The other big thing that I loved about Lily was that she never questioned her sanity. As much as she recognized that having Iris was abnormal, she never worried that it meant that something was wrong with her; it was merely something she knew she should keep to herself in order to keep everyone happy. While I personally would have appreciated a psychological twist to The Shadow Girl’s plot, it probably would have been a little too much considering everything else that was going on!There’s definitely more I could say, like certain ethical questions that were raised, but I don’t want to get into spoilers. Thanks to a relatable and headstrong heroine, and enough mystery and suspense to keep me on edge for most of its pages, The Shadow Girl is a must read!