Barbara Stewart’s The In-Between begins when Ellie, along with her mom, dad, and her cat, are in a car accident in the Poconos. They were moving from a small town in Pennsylvania to a smaller town in New York, where dad was taking a new job, mom was studying for her real estate license, and where Ellie could get a fresh start. Fourteen-year-old Ellie was — and is — troubled. Best friend Priscilla wasn’t the friend she thought she was, and she went through her life in a state of unease, disappointment, and ultimately, she attempted suicide as a means out. But the car accident puts everything into a different type of tail spin. Just as things felt like they could be a fresh start, they’re not.

When Ellie awakes and finds herself in her new home, she’s visited by the ghost of her deceased mother. The car accident had killed her and left just Ellie and her father to build a new life together. But Ellie sensed mom all around her; mom often pressed into her palm, reassuring her that even in the afterlife, her presence was still around.

So was the presence of Madeline.

Madeline was everything Ellie ever wanted to be. Stylish. Fun. A little bit wild and unashamed. This was not just who Ellie hoped to be in her new town, but Madeline was also the kind of person Ellie wanted to be friends with. They spent countless hours together, and it was Madeline who Ellie opened up to about everything: her broken friendships back in her old town, her depression, her suicide attempt, everything. Ellie and Madeline’s relationship bordered on obsessive; Ellie couldn’t stop thinking about her and desiring to be with her at all times. She even let Madeline tattoo her body with an “ME” over he heart — “ME” standing, of course, for “Madeline” and “Ellie.” Mostly.

But Ellie’s father wasn’t the one who survived the accident. He died. He never got to be at the new house. Ellie’s mother was the one who lived. So when Ellie wakes up — really wakes up — from the accident, everything in the house feels familiar, but her father isn’s there. Her mother is. And Madeline isn’t really there either. Except her presence is. On top of the weird and unnerving deja vu, Ellie has to be nice to Autumn, a girl who lives near her, who her mother wants her to be friend, and who is too much like the people back in her old town that she didn’t like. Fortunately, Ellie also meets Jess, a popular girl. But Jess won’t befriend her, not really. And Autumn will get a very different impression of Ellie when Ellie admits to trying to kill herself, to the strange visions she’s seen, and to Madeline.

It’s a sonogram in a box of items that makes things snap into place for Ellie. First when she discovers it in her afterlife with her dad, and second, when she confronts her mother about it. But mom isn’t forthcoming. Mom won’t be forthcoming. Mom insists Ellie mind her own business, get herself together to be the New Ellie she’s supposed to be in her new life, and spend more time with Autumn as a means to get there.

Ellie can’t stop thinking about Madeline. Can’t stop embodying her spirit. Can’t stop embodying her.

The In-Between is wonderfully complex — as a reader you’re never sure what reality Ellie is taking you through. Is she mentally ill? Is this a side effect of the car accident, in that she’s seeing and connecting with spirits that reside in her mind? Or is Ellie truly being visited by a ghost in this new place? There are many layers to this cake, and each one makes sense alone. Together, they blur the lines between reality and madness, between mental illness and the supernatural. I love books that do this, forcing the reader to consider the lines between what mental illness is and what the supernatural may be. In many ways, Stewart’s novel is reminiscent of Nova Ren Suma’s Imaginary Girls or 17 & Gone because of this.

There aren’t answers here, either, so spending time trying to find an explanation isn’t worthwhile. The story is about that unknowing, that line in between madness and sanity. Between the real world and the not-so-real world. Is there a distinction? Should there be one? Does it matter?

Of course, Ellie offers ideas, and the way the book is written, she is in many ways addressing a readership. This isn’t a diary. But maybe it is a diary. It’s never entirely clear whether Ellie is alive or dead. Whether Madeline is the one alive or dead. Plenty of the holes in the story could lead readers to believe either story or explanation. Ellie isn’t entirely reliable, and we know this near-immediately. We first believe she’s living with her father in the new house, then we’re told shortly after that she’s living with her mother. That her mother is pregnant with twins.

Twins.

Stewart weaves into the story an element about twins. The sonogram Ellie discovers shows that when she was in utero, she wasn’t alone. She’d had a twin, but that twin had disappeared. There hadn’t been a miscarriage; it was vanishing twin syndrome. Armed with that knowledge, as well as her own experiences with depression and suicide, Ellie tells herself that the reason for her life never being good was because she was a murderer event before she was born. That because of her, her twin sister Madeline never got the chance to live. That because of her, the good girl, the cool girl, the one who would have been popular and well-liked and a good daughter never got the chance to exist. Instead, she can only exist in the mind of Ellie and within the body of Ellie.

Ellie is just her carrier.

Mom being pregnant with twins post-accident, post-death of her father, is both the best thing and the worst thing Ellie can imagine. The best because her siblings will have one another. The worst because what does that leave Ellie? Ultimately, it is those twins — and what happens to them — that forces Ellie to confront Madeline head-on. And, ultimately, it’s where the story leaves readers wondering what just happened, what will happen, and whether we’ve been taken on a wild ride with Ellie’s mental illness.

Stewart’s writing is crisp, tight, and completely believable. Many YA books featuring younger teen protagonists can miss the mark. Here, Ellie is 14. Though the book does tackle the creepy head on, and though Ellie does discuss her suicide attempt and does participate in an act of violence, the book is suitable for younger teen readers. The story is a trip, and because it’s not one which has any solid resolution, it will frustrate those readers who seek answers. Fortunately, many readers who love darker stories, who love horror and the supernatural and ghosts, will be very satisfied with how many possibilities exist in this book. Because what is living? What is death? Can we exist in a world between the two of them and interact with both sides? Does mental illness hold the power to allow both sides in?

And perhaps “ME” means something greater than simply Madeline and Ellie.

Pass this off to readers who love Nova Ren Suma’s Imaginary Girls or 17 & Gone. In many ways, this reminded me of Sarah McCarry’s All Our Pretty Songs in terms of writing — it’s got a magical quality to it that doesn’t override the story.

Review copy received via the publisher. The In-Between will be available November 5 from St. Martin’s Press.